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Re: [Wlug] Dec Meeting announcement / linux-raid problem

by John Stoffel

>>>>> "Eric" == Eric Martin <eric.joshua.martin(a)gmail.com> writes: Eric> Now, the main reason for my email. My mythbox / home file Eric> server runs linux soft-raid in RAID5 with 3 500GB disks. One Eric> disk went bad a while ago and the array never rebuilt itself. So you only had two 500Gb disks left in the array? Eric> The other day, the second disk went bad. Am I hosed? Possibly, it depends on how bad the second disk is. What I would do is try to use dd_rescue to copy the 2nd bad disk onto a new disk (possibly your original bad disk if you feel brave!) and then try to re-assemble your raid 5 using that. You might or might not have corruption in the filesystem, so make sure you run an fsck on it. Now, in the future, you should run a weekly check of the array for bad blocks or other problems, so that you get notified if a disk dies silently. I use the following crontab entry: # # cron.d/mdadm -- schedules periodic redundancy checks of MD devices # # Copyright © martin f. krafft <madduck(a)madduck.net> # distributed under the terms of the Artistic Licence 2.0 # # By default, run at 00:57 on every Sunday, but do nothing unless the day of # the month is less than or equal to 7. Thus, only run on the first Sunday of # each month. crontab(5) sucks, unfortunately, in this regard; therefore this # hack (see #380425). 57 0 * * 0 root if [ -x /usr/share/mdadm/checkarray ] && [ $(date +\%d) -le 7 ]; then /usr/share/mdadm/checkarray --cron --all --idle --quiet; fi and I get a nice weekly report on both arrays on my main filerserver at thome. Eric> I've been googling for 'rebuild bad linux software raid' but all Eric> I get is the rebuild command. Also, I don't see any tools that Eric> will move bad data to another spot on the disk. This is my Eric> first time using software raid so I'm in a bit over my head. The first thing is to ask for help on the linux-raid mailing list, which is hosted on vger.kernel.org. But somethings you can do to help is to give us more information. Like: cat /proc/mdstat mdadm -E /dev/sd... or /dev/hd... depending on whether your SATA or IDE drives. Basically, use the devices you got from the /proc/mdstat output as your basis. Give us this output, and we should be able to help you more. John

Dec. 20, 2010

Re: [Wlug] disk/Raid ideas

by Theo Van Dinter

Did the second drive completely fail or is it just a bad block? Does the array work at all? If the disk is marked bad (RAID metadata), then maybe you can mark it as ok, get the array online, and copy off as much data as possible (starting with the most important files first, of course). You may be able to dd the data per disk, skipping any bad blocks, to another disk and then possibly be able to access some of the array that way. And of course ... you do have a backup of that data somewhere, right? :) In general, some rules of thumb are: - RAID is not a replacement for backups - RAID 5 becomes more problematic as disk sizes + number of disks increase, look at something like RAID 6 (raid-dp, raidz2, whatever your implementation calls it) instead. - Be aggressive about fixing bad disks in order to shorten the catastrophe window. On Sat, Dec 18, 2010 at 1:03 PM, Eric Martin <eric.joshua.martin(a)gmail.com> wrote: > It's raid 5, and I can't recover the group because of a hd error on two > disks. I wanted to see if I could move that data somewhere else to force a > rebuild but it looks like a no. Oh well, to the backup drive. > > On Sat, Dec 18, 2010 at 1:00 PM, Jason Couture <plaguethenet(a)gmail.com> > wrote: >> >> What kind of raid? If it was raid 5 I don't believe you can rebuild the >> array unless you have 2 surviving disks, so unless you can somehow recover >> one of the other two it would seem you are sol. Been a long time since I've >> done anything but 0, 1 and 0+1 so I could be wrong. >> >> Sent from my android wireless device. >> >> On Dec 18, 2010 12:48 PM, "Doug Mildram" <dmildram(a)gmail.com> wrote: >> >> You're hosed (i think) unless >> >> -- you're rich and you send the disks to a shop for megabucks (they may >> start with a trivial purchase of 2-3 identical model disks) >> >> -- OR IF your problem was NOT the actual platters/heads, YOU obtain 1-2 >> same-model disks, swap the board from a replacement disk onto your hosed >> disk ( w/ sm torx tool and brave fingers ) >> >> I've not done this myself yet. >> >> I HAVE had "stiction" problems where (after a power out or a "rest" so a >> disk bearing/lubricant gets a chance to harden) the disk just isnt spinning >> up. Of course, tapping/whacking it at the right/initial moment will usually >> cure that and you can feel if it's spinning or not....if you can hold it in >> your hand ...OR somehow get hands-on during powerup. >> >> >> >> _______________________________________________ >> Wlug mailing list >> Wlug(a)mail.wlug.org >> http://mail.wlug.org/mailman/listinfo/wlug >> >> >> _______________________________________________ >> Wlug mailing list >> Wlug(a)mail.wlug.org >> http://mail.wlug.org/mailman/listinfo/wlug >> > > > > -- > Eric Martin > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > >

Dec. 19, 2010

Re: [Wlug] Dec Meeting announcement / linux-raid problem

by soup

I don't run software raid so I'm not sure how it handles filesystem errors but I've used ddrescue to recover drives/arrays that were written off. It's fairly easy to use but can take quite a while depending on what the drive failure was. Simple bad sectors in a bad place it will usually chew through pretty quick, though. Take care, James On 12/18/2010 1:01 PM, Eric Martin wrote: > I have backups of some stuff but I have a program that isn't great > about writing stuff properly so I wanted to see if I could get more. > If I can't it's ok, the backups will suffice. I was just hoping for > more :) The replacement is on it's way so this is a moot point pretty > fast. > > On Sat, Dec 18, 2010 at 11:28 AM, James Gray <jamespgray(a)gmail.com > <mailto:jamespgray@gmail.com>> wrote: > > It appears there has been very little traffic as of late. Did you > compare the messages you've received to the wlug archives? > http://mail.wlug.org/pipermail/wlug/ > > As for your RAID issue you I don't have any advice as I have virtually > no experience with it. I assume if you had backups you won't have > bothered writing the group. > > On Fri, Dec 17, 2010 at 6:30 AM, Eric Martin > <eric.joshua.martin(a)gmail.com > <mailto:eric.joshua.martin@gmail.com>> wrote: > > > > I just realized that I haven't received anything from WLUG in > over a month, including the announcement for this past meeting. > Did anybody else have this problem or is it just me? > > > > Now, the main reason for my email. My mythbox / home file > server runs linux soft-raid in RAID5 with 3 500GB disks. One disk > went bad a while ago and the array never rebuilt itself. The > other day, the second disk went bad. Am I hosed? I've been > googling for 'rebuild bad linux software raid' but all I get is > the rebuild command. Also, I don't see any tools that will move > bad data to another spot on the disk. This is my first time using > software raid so I'm in a bit over my head. > > > > thanks! > > > > -- > > Eric Martin > > > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org <mailto:Wlug@mail.wlug.org> > > http://mail.wlug.org/mailman/listinfo/wlug > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org <mailto:Wlug@mail.wlug.org> > http://mail.wlug.org/mailman/listinfo/wlug > > > > > -- > Eric Martin > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug

Dec. 19, 2010

Re: [Wlug] Dec Meeting announcement / linux-raid problem

by Jason Couture

I hear you man, good luck. At least you had the backups. Sent from my android wireless device. On Dec 18, 2010 1:02 PM, "Eric Martin" <eric.joshua.martin(a)gmail.com> wrote: I have backups of some stuff but I have a program that isn't great about writing stuff properly so I wanted to see if I could get more. If I can't it's ok, the backups will suffice. I was just hoping for more :) The replacement is on it's way so this is a moot point pretty fast. On Sat, Dec 18, 2010 at 11:28 AM, James Gray <jamespgray(a)gmail.com> wrote: > > It appears there ha... -- Eric Martin _______________________________________________ Wlug mailing list Wlug(a)mail.wlug.org http://mail.wlug.org/mailman/listinfo/wlug

Dec. 18, 2010

Re: [Wlug] disk/Raid ideas

by Eric Martin

It's raid 5, and I can't recover the group because of a hd error on two disks. I wanted to see if I could move that data somewhere else to force a rebuild but it looks like a no. Oh well, to the backup drive. On Sat, Dec 18, 2010 at 1:00 PM, Jason Couture <plaguethenet(a)gmail.com>wrote: > What kind of raid? If it was raid 5 I don't believe you can rebuild the > array unless you have 2 surviving disks, so unless you can somehow recover > one of the other two it would seem you are sol. Been a long time since I've > done anything but 0, 1 and 0+1 so I could be wrong. > > Sent from my android wireless device. > > On Dec 18, 2010 12:48 PM, "Doug Mildram" <dmildram(a)gmail.com> wrote: > > You're hosed (i think) unless > > -- you're rich and you send the disks to a shop for megabucks (they may > start with a trivial purchase of 2-3 identical model disks) > > -- OR IF your problem was NOT the actual platters/heads, YOU obtain 1-2 > same-model disks, swap the board from a replacement disk onto your hosed > disk ( w/ sm torx tool and brave fingers ) > > I've not done this myself yet. > > I HAVE had "stiction" problems where (after a power out or a "rest" so a > disk bearing/lubricant gets a chance to harden) the disk just isnt spinning > up. Of course, tapping/whacking it at the right/initial moment will usually > cure that and you can feel if it's spinning or not....if you can hold it in > your hand ...OR somehow get hands-on during powerup. > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > > -- Eric Martin

Dec. 18, 2010

Re: [Wlug] Dec Meeting announcement / linux-raid problem

by Eric Martin

I have backups of some stuff but I have a program that isn't great about writing stuff properly so I wanted to see if I could get more. If I can't it's ok, the backups will suffice. I was just hoping for more :) The replacement is on it's way so this is a moot point pretty fast. On Sat, Dec 18, 2010 at 11:28 AM, James Gray <jamespgray(a)gmail.com> wrote: > It appears there has been very little traffic as of late. Did you > compare the messages you've received to the wlug archives? > http://mail.wlug.org/pipermail/wlug/ > > As for your RAID issue you I don't have any advice as I have virtually > no experience with it. I assume if you had backups you won't have > bothered writing the group. > > On Fri, Dec 17, 2010 at 6:30 AM, Eric Martin > <eric.joshua.martin(a)gmail.com> wrote: > > > > I just realized that I haven't received anything from WLUG in over a > month, including the announcement for this past meeting. Did anybody else > have this problem or is it just me? > > > > Now, the main reason for my email. My mythbox / home file server runs > linux soft-raid in RAID5 with 3 500GB disks. One disk went bad a while ago > and the array never rebuilt itself. The other day, the second disk went > bad. Am I hosed? I've been googling for 'rebuild bad linux software raid' > but all I get is the rebuild command. Also, I don't see any tools that will > move bad data to another spot on the disk. This is my first time using > software raid so I'm in a bit over my head. > > > > thanks! > > > > -- > > Eric Martin > > > > _______________________________________________ > > Wlug mailing list > > Wlug(a)mail.wlug.org > > http://mail.wlug.org/mailman/listinfo/wlug > > > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > -- Eric Martin

Dec. 18, 2010

Re: [Wlug] disk/Raid ideas

by Jason Couture

What kind of raid? If it was raid 5 I don't believe you can rebuild the array unless you have 2 surviving disks, so unless you can somehow recover one of the other two it would seem you are sol. Been a long time since I've done anything but 0, 1 and 0+1 so I could be wrong. Sent from my android wireless device. On Dec 18, 2010 12:48 PM, "Doug Mildram" <dmildram(a)gmail.com> wrote: You're hosed (i think) unless -- you're rich and you send the disks to a shop for megabucks (they may start with a trivial purchase of 2-3 identical model disks) -- OR IF your problem was NOT the actual platters/heads, YOU obtain 1-2 same-model disks, swap the board from a replacement disk onto your hosed disk ( w/ sm torx tool and brave fingers ) I've not done this myself yet. I HAVE had "stiction" problems where (after a power out or a "rest" so a disk bearing/lubricant gets a chance to harden) the disk just isnt spinning up. Of course, tapping/whacking it at the right/initial moment will usually cure that and you can feel if it's spinning or not....if you can hold it in your hand ...OR somehow get hands-on during powerup. _______________________________________________ Wlug mailing list Wlug(a)mail.wlug.org http://mail.wlug.org/mailman/listinfo/wlug

Dec. 18, 2010

disk/Raid ideas

by Doug Mildram

You're hosed (i think) unless -- you're rich and you send the disks to a shop for megabucks (they may start with a trivial purchase of 2-3 identical model disks) -- OR IF your problem was NOT the actual platters/heads, YOU obtain 1-2 same-model disks, swap the board from a replacement disk onto your hosed disk ( w/ sm torx tool and brave fingers ) I've not done this myself yet. I HAVE had "stiction" problems where (after a power out or a "rest" so a disk bearing/lubricant gets a chance to harden) the disk just isnt spinning up. Of course, tapping/whacking it at the right/initial moment will usually cure that and you can feel if it's spinning or not....if you can hold it in your hand ...OR somehow get hands-on during powerup.

Dec. 18, 2010

Re: [Wlug] Dec Meeting announcement / linux-raid problem

by James Gray

It appears there has been very little traffic as of late. Did you compare the messages you've received to the wlug archives? http://mail.wlug.org/pipermail/wlug/ As for your RAID issue you I don't have any advice as I have virtually no experience with it. I assume if you had backups you won't have bothered writing the group. On Fri, Dec 17, 2010 at 6:30 AM, Eric Martin <eric.joshua.martin(a)gmail.com> wrote: > > I just realized that I haven't received anything from WLUG in over a month, including the announcement for this past meeting. Did anybody else have this problem or is it just me? > > Now, the main reason for my email. My mythbox / home file server runs linux soft-raid in RAID5 with 3 500GB disks. One disk went bad a while ago and the array never rebuilt itself. The other day, the second disk went bad. Am I hosed? I've been googling for 'rebuild bad linux software raid' but all I get is the rebuild command. Also, I don't see any tools that will move bad data to another spot on the disk. This is my first time using software raid so I'm in a bit over my head. > > thanks! > > -- > Eric Martin > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 18, 2010

Dec Meeting announcement / linux-raid problem

by Eric Martin

I just realized that I haven't received anything from WLUG in over a month, including the announcement for this past meeting. Did anybody else have this problem or is it just me? Now, the main reason for my email. My mythbox / home file server runs linux soft-raid in RAID5 with 3 500GB disks. One disk went bad a while ago and the array never rebuilt itself. The other day, the second disk went bad. Am I hosed? I've been googling for 'rebuild bad linux software raid' but all I get is the rebuild command. Also, I don't see any tools that will move bad data to another spot on the disk. This is my first time using software raid so I'm in a bit over my head. thanks! -- Eric Martin

Dec. 17, 2010

Reminder: WLUG Meeting tonight! (11/10)

by Tim Keller

Hey Gang, Tonight we've got a WLUG meeting in the conference room adjacent to the Morgan Hall dining room at ~7PM. Though we're usually there a bit earlier. As of yet, there's no designated speaker so it'll be a round table discussion, unless someone steps forward, the floors open. Following protocol there will be consumption of pizza afterward. Hope to see you there! Tim. -- I am leery of the allegiances of any politician who refers to their constituents as "consumers".

Nov. 10, 2010

Re: [Wlug] Best 802.11abgn router?

by Jim Dibb

On Thu, Oct 14, 2010 at 12:39 PM, John Stoffel <john(a)stoffel.org> wrote: > >>>>> "Adam" == Adam Gomes <adam(a)unixgeek.net> writes: > > Adam>> Ugh, wireless can be such a head ache. Dude, John, just run some > Adam>> cables. > > John>Actually, that's what I ended up doing last night, once I figured out > that spending $150 for a new router (which I'd have to wait for to > arrive from the egg...) wasn't going to work as well as just pulling > 70' of cable. > > After fighting with all kinds of wireless latency and connectivity issues (and multiple wireless dongles, routers and even powerline networking) , I ran 100' of pre-terminated, burial grade Cat6 around the outside of my house to the diagonally opposite corner and haven't looked back. Jim

Oct. 14, 2010

Re: [Wlug] Best 802.11abgn router?

by John Stoffel

>>>>> "Adam" == Adam Gomes <adam(a)unixgeek.net> writes: Adam> I live in the middle of the woods, and I generally discourage Adam> the use of things like bluetooth at my house. So, 2.4Ghz works Adam> ok for me. But if you actually have neighbors, and own / use a Adam> microwave oven, and use bluetooth gadgetry, and any other number Adam> of things that can / do emit into the 2.4Ghz spectrum, I have to Adam> agree with Frank. Put your 11n traffic into the 5Ghz space, and Adam> leave everyone else in the 2.4Ghz space. 2.4Ghz is noisy and Adam> crowded and just not a lot of fun. Adam> I have a long list of funny / disheartening storries about Adam> 2.4Ghz and wifi at a number of my employer's locations .... Adam> Frank, good point too about the channel width. And 802.11ac puts Adam> 80 and 160 Mhz channels on the horizon .. but ... who gives a Adam> hoot, when (if you choose to play nice with others) you still Adam> have to honor those neighbors of your using the 20Mhz channel Adam> width? Adam> Ugh, wireless can be such a head ache. Dude, John, just run some Adam> cables. Actually, that's what I ended up doing last night, once I figured out that spending $150 for a new router (which I'd have to wait for to arrive from the egg...) wasn't going to work as well as just pulling 70' of cable. So now the wife is running at GigE speeds internally, and she seems a little bit happier. I'll know more tonight since I just got it working this morning. John

Oct. 14, 2010

Re: [Wlug] Best 802.11abgn router?

by Adam Gomes

I live in the middle of the woods, and I generally discourage the use of things like bluetooth at my house. So, 2.4Ghz works ok for me. But if you actually have neighbors, and own / use a microwave oven, and use bluetooth gadgetry, and any other number of things that can / do emit into the 2.4Ghz spectrum, I have to agree with Frank. Put your 11n traffic into the 5Ghz space, and leave everyone else in the 2.4Ghz space. 2.4Ghz is noisy and crowded and just not a lot of fun. I have a long list of funny / disheartening storries about 2.4Ghz and wifi at a number of my employer's locations .... Frank, good point too about the channel width. And 802.11ac puts 80 and 160 Mhz channels on the horizon .. but ... who gives a hoot, when (if you choose to play nice with others) you still have to honor those neighbors of your using the 20Mhz channel width? Ugh, wireless can be such a head ache. Dude, John, just run some cables. --Adam On Wed, Oct 13, 2010 at 4:57 PM, Chuck Anderson <cra(a)wpi.edu> wrote: > On Wed, Oct 13, 2010 at 11:34:34AM -0400, Frank Sweetser wrote: > > On 10/13/2010 11:23 AM, John Stoffel wrote: > > > > > My only worry is that all my core network is in the basement, but I > > > have my current WAP upstairs in a central-ish location. And my wife's > > > wireless is upstairs too... But replacing my WRAP board with something > > > with more ports which I can break out more would be good > > > to... decisions, decisions... > > > > > > Can you put different antennas on the netgear? > > > > Not on this particular model, no. Sadly, there aren't very many external > 11n > > antenna options on the market yet. That said, 11n does have a little > better > > penetration than a/b/g, so it may work out for you anyway. I have mine > in my > > basement, and it works quite well in my 2nd floor bedroom. > > > > > Thanks for all the feedback, now I'm leaning Netgear... :] > > Many of the new Netgears actually run a modified OpenWRT from the > factory (the older 7.x version from what I can tell on my WNDR3700). > > A nice 2.4-only 3x3 AP with external antenna connectors is the TP-Link > TL-1043ND. It also runs OpenWRT from the factory. Sadly, this one > isn't reviewed on smallnetbuilder.com. > > Another forum with router/wireless hacking info on it: > > http://forums.whirlpool.net.au/ > > http://forums.whirlpool.net.au/forum/9?g=3 > > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Chuck Anderson

On Wed, Oct 13, 2010 at 11:34:34AM -0400, Frank Sweetser wrote: > On 10/13/2010 11:23 AM, John Stoffel wrote: > > > My only worry is that all my core network is in the basement, but I > > have my current WAP upstairs in a central-ish location. And my wife's > > wireless is upstairs too... But replacing my WRAP board with something > > with more ports which I can break out more would be good > > to... decisions, decisions... > > > > Can you put different antennas on the netgear? > > Not on this particular model, no. Sadly, there aren't very many external 11n > antenna options on the market yet. That said, 11n does have a little better > penetration than a/b/g, so it may work out for you anyway. I have mine in my > basement, and it works quite well in my 2nd floor bedroom. > > > Thanks for all the feedback, now I'm leaning Netgear... :] Many of the new Netgears actually run a modified OpenWRT from the factory (the older 7.x version from what I can tell on my WNDR3700). A nice 2.4-only 3x3 AP with external antenna connectors is the TP-Link TL-1043ND. It also runs OpenWRT from the factory. Sadly, this one isn't reviewed on smallnetbuilder.com. Another forum with router/wireless hacking info on it: http://forums.whirlpool.net.au/ http://forums.whirlpool.net.au/forum/9?g=3

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Frank Sweetser

On 10/13/2010 11:23 AM, John Stoffel wrote: > My only worry is that all my core network is in the basement, but I > have my current WAP upstairs in a central-ish location. And my wife's > wireless is upstairs too... But replacing my WRAP board with something > with more ports which I can break out more would be good > to... decisions, decisions... > > Can you put different antennas on the netgear? Not on this particular model, no. Sadly, there aren't very many external 11n antenna options on the market yet. That said, 11n does have a little better penetration than a/b/g, so it may work out for you anyway. I have mine in my basement, and it works quite well in my 2nd floor bedroom. > Thanks for all the feedback, now I'm leaning Netgear... :] -- Frank Sweetser fs at wpi.edu | For every problem, there is a solution that WPI Senior Network Engineer | is simple, elegant, and wrong. - HL Mencken GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Frank Sweetser

On 10/13/2010 11:04 AM, Adam Gomes wrote: > Are there really any affordable consumer grade wireless adapters that have the > capability of four spatial streams? I ask because if there aren't then paying Doubtful, on both the AP and client end. Even the high grade commercial stuff that we're deploying on campus doesn't come higher than 3x3. A quick google search shows that 4x4 chipsets are just now being bragged about by Marvell, which means that they're not going to be widespread in on the shelf products for probably another year or so. > the premium for "600N" maybe be a waste. I know that Intel started selling 600N is nothing more than a marketing label these days. For example, on the 3700, the "600" number was from adding up 300 on 2.4 plus 300 on 5. Not technically wrong, but... well, marketing. 99% of what you're buying out there is going to be 2x2, which maxes out at an on-paper speed of 300Mbit, or about 160Mbit of real work useful throughput. > relatively affordable 3x3:3 cards, but that's still going to cap-out at 450MB > for MAC/PHY layer speeds. To me, what's more important is having simultaneous > access to both bands (2.4Ghz, and 5.1Ghz) so I can avoid interference when > possible. Anything over a single 150MB spatial stream at that point is just > gravy. Especially since most of my network at home is still 10/100, and most > of my larger data transfers are over the Internet ... so well, no ISP around > me offers speed in excess of 100MB sustained. :) You should also be aware that there are other variables that factor into the speed, including inter frame spacing and channel width (20MHz vs 40MHz), and the RF environment. Traditional wireless with a single spatial stream (11a/b/g) requires a good, strong single signal between the endpoints. 11n, on the other hand, supports MIMO. Basically it sends out multiple streams on the same channel (up to four in the specs) and then depends on having the different streams bounce around slightly differently. For example, stream A may be strongest on the direct path, while stream B may be a little stronger bouncing off a nearby fridge. MIMO then performs dark magic to use these different properties to split the streams back out, allowing them to carry different data. If you don't have a good diverse RF environment, it's quite possible that your 4x4 degrades down to an effect 2x2. With 11n, sitting 10 feet away from the AP in a big empty nothing is not going be near best case performance. > Well, there's that, and since a number of devices in my house are still > 802.11b/g only devices (e.g. my Wii), and there are just so many of these wifi > enabled devices, I don't expect to get close to the top end throughput rates > on these newer 'n' capable APs anyway. That is to say, while operating in the > 2.4Ghz space, I'm still going to have to wait for my 54MB devices to send > their frames before I get the chance to transmit my frames at 150 - 600MB. > Just having that second 5Ghz band and singel spatial stream is good enough, I > think. Make sense? Just having legacy clients associated at all will absolutely drag your throughput down. You're best off trying to keep the legacy clients on 2.4, and focus on putting new 11n stuff on 5, to keep it operating in pure 11n mode. At that point, a typical 2x2 device should give you plenty of performance. -- Frank Sweetser fs at wpi.edu | For every problem, there is a solution that WPI Senior Network Engineer | is simple, elegant, and wrong. - HL Mencken GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by John Stoffel

>>>>> "Frank" == Frank Sweetser <fs(a)WPI.EDU> writes: Frank> On 10/13/2010 10:48 AM, John Stoffel wrote: >>>>>>> "Frank" == Frank Sweetser <fs(a)WPI.EDU> writes: >> Frank> On 10/13/2010 10:26 AM, John Stoffel wrote: >>>> >>>> Guys, >>>> >>>> I'm looking to replace my WAP54G (802.11bg) wireless access point. I >>>> really need to get more speed to the wife's computer, and I don't want >>>> to run wires. >>>> >>>> I'm thinking I'd like to get something that DD-WRT can run on, and >>>> possibly something with dual radios and/or dual 2.4ghz and 5.0ghz >>>> band, so I can have a secured network, and an open, slower network for >>>> guests. >>>> >>>> My home network looks like this: >>>> >>>> cable modem <---> router <----> GigE Lan switch <-- clients >>>> | >>>> | >>>> WAP54G >> Frank> Congratulations, you're me a month ago =) >> >> Heh, so where do you end up putting your new wireless router in your >> network? Did you replace the core router, or add on? Yeah I'm a >> professional SysAdmin, but I don't do the network side day to >> day... so I want to stay secure. Probably way too paranoid, but >> that's me. Frank> I threw out everything else and I'm just using the netgear for Frank> everything. I didn't bother to set it up, but openwrt does Frank> support setting up a second guest wireless network if you want Frank> to segment guests off from your own machines. My only worry is that all my core network is in the basement, but I have my current WAP upstairs in a central-ish location. And my wife's wireless is upstairs too... But replacing my WRAP board with something with more ports which I can break out more would be good to... decisions, decisions... Can you put different antennas on the netgear? Thanks for all the feedback, now I'm leaning Netgear... :]

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Adam Gomes

Are there really any affordable consumer grade wireless adapters that have the capability of four spatial streams? I ask because if there aren't then paying the premium for "600N" maybe be a waste. I know that Intel started selling relatively affordable 3x3:3 cards, but that's still going to cap-out at 450MB for MAC/PHY layer speeds. To me, what's more important is having simultaneous access to both bands (2.4Ghz, and 5.1Ghz) so I can avoid interference when possible. Anything over a single 150MB spatial stream at that point is just gravy. Especially since most of my network at home is still 10/100, and most of my larger data transfers are over the Internet ... so well, no ISP around me offers speed in excess of 100MB sustained. :) Well, there's that, and since a number of devices in my house are still 802.11b/g only devices (e.g. my Wii), and there are just so many of these wifi enabled devices, I don't expect to get close to the top end throughput rates on these newer 'n' capable APs anyway. That is to say, while operating in the 2.4Ghz space, I'm still going to have to wait for my 54MB devices to send their frames before I get the chance to transmit my frames at 150 - 600MB. Just having that second 5Ghz band and singel spatial stream is good enough, I think. Make sense? On Wed, Oct 13, 2010 at 10:53 AM, Frank Sweetser <fs(a)wpi.edu> wrote: > On 10/13/2010 10:48 AM, John Stoffel wrote: > >>>>>> "Frank" == Frank Sweetser <fs(a)WPI.EDU> writes: > > > > Frank> On 10/13/2010 10:26 AM, John Stoffel wrote: > >>> > >>> Guys, > >>> > >>> I'm looking to replace my WAP54G (802.11bg) wireless access point. I > >>> really need to get more speed to the wife's computer, and I don't want > >>> to run wires. > >>> > >>> I'm thinking I'd like to get something that DD-WRT can run on, and > >>> possibly something with dual radios and/or dual 2.4ghz and 5.0ghz > >>> band, so I can have a secured network, and an open, slower network for > >>> guests. > >>> > >>> My home network looks like this: > >>> > >>> cable modem <---> router <----> GigE Lan switch <-- clients > >>> | > >>> | > >>> WAP54G > > > > Frank> Congratulations, you're me a month ago =) > > > > Heh, so where do you end up putting your new wireless router in your > > network? Did you replace the core router, or add on? Yeah I'm a > > professional SysAdmin, but I don't do the network side day to > > day... so I want to stay secure. Probably way too paranoid, but > > that's me. > > I threw out everything else and I'm just using the netgear for everything. > I > didn't bother to set it up, but openwrt does support setting up a second > guest > wireless network if you want to segment guests off from your own machines. > > > > Frank> The only glitch there is that it's a little more strict about > > Frank> wireless security behaviour, so some non-compliant devices > > Frank> (droid1 phones running android 2.2, in my case) can't associate > > Frank> at WPA2/AES. > > > > Bummers. :] That's why I figure I'll keep around my old WAP54G for > > wep devices and stuff that I don't care about much. > > I was able to get them running by limiting encryption down to WPA/TKIP. Of > course, AES is required for 11n speeds, so I'll be mucking around with this > more when either the phones or the router has a new update available =) > > > Frank> I've heard very good things about the buffalo devices, > > Frank> especially since they ship with dd-wrt from the factory. They > > Frank> don't have the same performance (again, smallnetbuilder has > > Frank> excellent benchmarks for side by side comparisons), but are a > > Frank> lot cheaper. One drawback of that particular model at least is > > Frank> that it's single band, 2.4GHz only. Personally I strongly > > Frank> recommend going with a dual band device, as 2.4 these days > > Frank> tends to be a pea soup of interference, while the 5GHz bands > > Frank> that 11a uses has a lot more open channels available. > > > > Yeah, I think I really want dual band, dual radio, gigabit. Going to > > have to pay for it though. But if the device lasts, I'm not too > > upset. > > Yeah, that's exactly why I opted to pony up for the netgear (about $150) > instead of the cheaper buffalo. > > -- > Frank Sweetser fs at wpi.edu | For every problem, there is a solution > that > WPI Senior Network Engineer | is simple, elegant, and wrong. - HL > Mencken > GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Frank Sweetser

On 10/13/2010 10:48 AM, John Stoffel wrote: >>>>>> "Frank" == Frank Sweetser <fs(a)WPI.EDU> writes: > > Frank> On 10/13/2010 10:26 AM, John Stoffel wrote: >>> >>> Guys, >>> >>> I'm looking to replace my WAP54G (802.11bg) wireless access point. I >>> really need to get more speed to the wife's computer, and I don't want >>> to run wires. >>> >>> I'm thinking I'd like to get something that DD-WRT can run on, and >>> possibly something with dual radios and/or dual 2.4ghz and 5.0ghz >>> band, so I can have a secured network, and an open, slower network for >>> guests. >>> >>> My home network looks like this: >>> >>> cable modem <---> router <----> GigE Lan switch <-- clients >>> | >>> | >>> WAP54G > > Frank> Congratulations, you're me a month ago =) > > Heh, so where do you end up putting your new wireless router in your > network? Did you replace the core router, or add on? Yeah I'm a > professional SysAdmin, but I don't do the network side day to > day... so I want to stay secure. Probably way too paranoid, but > that's me. I threw out everything else and I'm just using the netgear for everything. I didn't bother to set it up, but openwrt does support setting up a second guest wireless network if you want to segment guests off from your own machines. > Frank> The only glitch there is that it's a little more strict about > Frank> wireless security behaviour, so some non-compliant devices > Frank> (droid1 phones running android 2.2, in my case) can't associate > Frank> at WPA2/AES. > > Bummers. :] That's why I figure I'll keep around my old WAP54G for > wep devices and stuff that I don't care about much. I was able to get them running by limiting encryption down to WPA/TKIP. Of course, AES is required for 11n speeds, so I'll be mucking around with this more when either the phones or the router has a new update available =) > Frank> I've heard very good things about the buffalo devices, > Frank> especially since they ship with dd-wrt from the factory. They > Frank> don't have the same performance (again, smallnetbuilder has > Frank> excellent benchmarks for side by side comparisons), but are a > Frank> lot cheaper. One drawback of that particular model at least is > Frank> that it's single band, 2.4GHz only. Personally I strongly > Frank> recommend going with a dual band device, as 2.4 these days > Frank> tends to be a pea soup of interference, while the 5GHz bands > Frank> that 11a uses has a lot more open channels available. > > Yeah, I think I really want dual band, dual radio, gigabit. Going to > have to pay for it though. But if the device lasts, I'm not too > upset. Yeah, that's exactly why I opted to pony up for the netgear (about $150) instead of the cheaper buffalo. -- Frank Sweetser fs at wpi.edu | For every problem, there is a solution that WPI Senior Network Engineer | is simple, elegant, and wrong. - HL Mencken GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by John Stoffel

>>>>> "Frank" == Frank Sweetser <fs(a)WPI.EDU> writes: Frank> On 10/13/2010 10:26 AM, John Stoffel wrote: >> >> Guys, >> >> I'm looking to replace my WAP54G (802.11bg) wireless access point. I >> really need to get more speed to the wife's computer, and I don't want >> to run wires. >> >> I'm thinking I'd like to get something that DD-WRT can run on, and >> possibly something with dual radios and/or dual 2.4ghz and 5.0ghz >> band, so I can have a secured network, and an open, slower network for >> guests. >> >> My home network looks like this: >> >> cable modem <---> router <----> GigE Lan switch <-- clients >> | >> | >> WAP54G Frank> Congratulations, you're me a month ago =) Heh, so where do you end up putting your new wireless router in your network? Did you replace the core router, or add on? Yeah I'm a professional SysAdmin, but I don't do the network side day to day... so I want to stay secure. Probably way too paranoid, but that's me. Frank> I got pointed at http://www.smallnetbuilder.com/ as a resource Frank> for comparing these devices. I ended up going with the Netgear Frank> WNDR3700, and have been very happy - ridiculous performance Frank> gains, including better internet performance. Nice. Frank> I do have to warn you that I tried dd-wrt on it, and it didn't Frank> work so great. It was a little flaky, and when I tried to Frank> upgrade it to a newer build, I semi-bricked it. (Luckily Frank> these boxes, when bricked, come up in a recovery mode where Frank> you can easily feed it a new image via TFTP, so bringing it Frank> back from the dead was trivial.) Instead I threw openwrt on Frank> it, with dnsmasq, dyndns, and openvpn configured, and it's Frank> been rock solid and blazingly fast. Interesting. I've been reading Newegg reviews and it's been interesting hearing that for some stuff openwrt is better than dd-wrt. Frank> The only glitch there is that it's a little more strict about Frank> wireless security behaviour, so some non-compliant devices Frank> (droid1 phones running android 2.2, in my case) can't associate Frank> at WPA2/AES. Bummers. :] That's why I figure I'll keep around my old WAP54G for wep devices and stuff that I don't care about much. Frank> I've heard very good things about the buffalo devices, Frank> especially since they ship with dd-wrt from the factory. They Frank> don't have the same performance (again, smallnetbuilder has Frank> excellent benchmarks for side by side comparisons), but are a Frank> lot cheaper. One drawback of that particular model at least is Frank> that it's single band, 2.4GHz only. Personally I strongly Frank> recommend going with a dual band device, as 2.4 these days Frank> tends to be a pea soup of interference, while the 5GHz bands Frank> that 11a uses has a lot more open channels available. Yeah, I think I really want dual band, dual radio, gigabit. Going to have to pay for it though. But if the device lasts, I'm not too upset. Frank> Chuck and I had talked about putting together some slides on Frank> openwrt, guess this means I should get started now... Go go go!

Oct. 13, 2010

Re: [Wlug] Best 802.11abgn router?

by Frank Sweetser

On 10/13/2010 10:26 AM, John Stoffel wrote: > > Guys, > > I'm looking to replace my WAP54G (802.11bg) wireless access point. I > really need to get more speed to the wife's computer, and I don't want > to run wires. > > I'm thinking I'd like to get something that DD-WRT can run on, and > possibly something with dual radios and/or dual 2.4ghz and 5.0ghz > band, so I can have a secured network, and an open, slower network for > guests. > > My home network looks like this: > > cable modem <---> router <----> GigE Lan switch <-- clients > | > | > WAP54G Congratulations, you're me a month ago =) > Unfortunately, my router is only 100mb/s on each port, which is fine > for WAN access, and most wireless, but not any more. And I don't want > to replace it since it's a WRAP board from PC-engines running m0n0wall > and doing a *great* job for what I need. Silent, no moving parts, > easy to manage. > > Mostly, I want a fast, secure wireless WPA2 home wireless network. > Maybe I'd keep the WAP54G around for public access... or maybe it's > time to bite the bullet and replace my WRAP board with something > better? > > I'm looking at the following: > > Netgear WNDR3700 > Linksys E2000 > Linksys WRT610N > ASUS RT-N16 > BUFFALO WZR-HP-G300NH (native DD-WRT support from factory!) I got pointed at http://www.smallnetbuilder.com/ as a resource for comparing these devices. I ended up going with the Netgear WNDR3700, and have been very happy - ridiculous performance gains, including better internet performance. I do have to warn you that I tried dd-wrt on it, and it didn't work so great. It was a little flaky, and when I tried to upgrade it to a newer build, I semi-bricked it. (Luckily these boxes, when bricked, come up in a recovery mode where you can easily feed it a new image via TFTP, so bringing it back from the dead was trivial.) Instead I threw openwrt on it, with dnsmasq, dyndns, and openvpn configured, and it's been rock solid and blazingly fast. The only glitch there is that it's a little more strict about wireless security behaviour, so some non-compliant devices (droid1 phones running android 2.2, in my case) can't associate at WPA2/AES. I've heard very good things about the buffalo devices, especially since they ship with dd-wrt from the factory. They don't have the same performance (again, smallnetbuilder has excellent benchmarks for side by side comparisons), but are a lot cheaper. One drawback of that particular model at least is that it's single band, 2.4GHz only. Personally I strongly recommend going with a dual band device, as 2.4 these days tends to be a pea soup of interference, while the 5GHz bands that 11a uses has a lot more open channels available. Chuck and I had talked about putting together some slides on openwrt, guess this means I should get started now... -- Frank Sweetser fs at wpi.edu | For every problem, there is a solution that WPI Senior Network Engineer | is simple, elegant, and wrong. - HL Mencken GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC

Oct. 13, 2010

Best 802.11abgn router?

by John Stoffel

Guys, I'm looking to replace my WAP54G (802.11bg) wireless access point. I really need to get more speed to the wife's computer, and I don't want to run wires. I'm thinking I'd like to get something that DD-WRT can run on, and possibly something with dual radios and/or dual 2.4ghz and 5.0ghz band, so I can have a secured network, and an open, slower network for guests. My home network looks like this: cable modem <---> router <----> GigE Lan switch <-- clients | | WAP54G Unfortunately, my router is only 100mb/s on each port, which is fine for WAN access, and most wireless, but not any more. And I don't want to replace it since it's a WRAP board from PC-engines running m0n0wall and doing a *great* job for what I need. Silent, no moving parts, easy to manage. Mostly, I want a fast, secure wireless WPA2 home wireless network. Maybe I'd keep the WAP54G around for public access... or maybe it's time to bite the bullet and replace my WRAP board with something better? I'm looking at the following: Netgear WNDR3700 Linksys E2000 Linksys WRT610N ASUS RT-N16 BUFFALO WZR-HP-G300NH (native DD-WRT support from factory!) Any hints or suggestions or feedback? Thanks, John

Oct. 13, 2010

Linux InstallFest

by Dignan, Patrick

Hi everyone, I've been a lurker on these lists for a while, but I wanted to let everyone know: WPI's ACM chapter is hosting a Linux Installfest on November 2 at 7:00PM. We expect to have a panel of Linux community members speaking prior to the installs. Last year we had an estimated turnout of 50-75 students. If any of you would like to join us for installation, to hear the community members speak, or just for moral support then please feel free! We will be meeting in Fuller Laboratories Room #320. Best, Patrick Dignan

Oct. 5, 2010

Re: [Wlug] New Memeber

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Joshua D. Demallistre wrote: > So, to make a story short I am a new member to this > group. I've been here, close to the Worcester area > and would like to meet with you guys. I have been > using Linux for the past 10 years without a LUG, so > this time I would like to do things differently, and get > together. Basically I wanted to say that I have been a > lone ranger for the last 10 year. I have been to the > website but there is no mentioned of the next > meeting. Hi Joshua, On the WLUG home page, click on the yellow box at the top that says "WLUG Meetings". This will take you to a page that lists the meeting dates so you can plan. The meeting topic is often not known until the last minute. Feel free to join us anytime! Andy - -- Andy Stewart (KB1OIQ) Founder: Worcester Linux Users' Group Founder: Chelmsford Linux Meetup Group President: PART of Westford, MA (WB1GOF) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iD8DBQFMoT+bOjiraCaOTOoRAtosAJ9/FRyfyYISwtdkgnGtMI5eNHZuzACg0Uuo z0Ufv8RVplkhnRmWk4eA2eY= =64zD -----END PGP SIGNATURE-----

Sept. 28, 2010