Carlton> I've done software RAID (RAID0 and RAID5) for a long time and Carlton> never had to use an initrd image. Just have a 100 MB boot Carlton> partition on one drive, and set root=/dev/md0 in grub. For me, the whole idea of booting of RAID is so that I can lose either disk, and not really notice. Currently, I don't have that. And since my main test system is also my main work system at home, I'm loathe to screw with it much. *grin* Carlton> This is with two 60GB WD HD's and one 80 GB (which has the Carlton> bootable 100 MB partition). If you RAID it all, well, guess Carlton> you need an initrd (please correct me if I'm wrong). As far as I know, yes you do need an initrd (or initramfs now?) to make it work properly. Carlton> As far as RAID1 and RAID5, isn't RAID5 strictly better, if Carlton> you have the HD's? I mean, just lose 1/3 of the storage for Carlton> total mirroring and you have to lose 2 HD's to lose your Carlton> data. Why would someone choose RAID1 over RAID5 (just Carlton> curious)? I did have a RAID5 system set up, but decided to Carlton> change it over to RAID0 and use an external Maxtor drive for Carlton> backup (just simple rsync). RAID0 = stripping RAID1 = mirroring RAID5 = parity RAID5 suffers on write performance when compared to RAID1, since if you write a small chunk of data, RAID5 may have to actually READ/COMPUTE PARITY/WRITE to all the drives. With RAID1, it's a simple parallel write to each drive. No READ overhead. RAID5 can generally just lose 1 disk from the set without losing data. RAID1 can lose 1/2 the mirror without losing data. How you implement your RAID1 setup across more than two disks is an issue. I choose RAID1 over RAID5 because I only had space for two drives, and I only had an HPT302 with dual channels, so I put one disk on each channel for maximum peformance. If I had more money and a 3ware controller, I probably would have gone for RAID5 on my data, since it has a size/cost advantage over RAID1. I would NEVER go for RAID0 for my data, too much potential for data loss. Even with backups. Carlton> Personally, I feel if you compile a couple of kernels it Carlton> really becomes old hat, I mean, once you know how to do it Carlton> it's no big deal. Same with RAID systems. But that would be Carlton> an interesting meeting, nonetheless. Exactly, it would be an interesting meeting to show people how easy it is to implement, and hopefully how robust it is as well, esp if you lose your primary harddisk. Can you boot cleanly from the secondary one? You have updated the MBR on that disk, right? Carlton> I've never had a problem and found I needed initrd to get Carlton> something to work. What are the benefits of using it?

From what I know, the advantage/requirement of using an initrd is that you can boot off of a funky device, since you first boot into a small OS image with all the tools you need to setup and switch to your main filesystems.

In my case, I've got a pair of 9gb SCSI disks, and I currently boot off one. My plan has always been to mirror the two disks so that if I lost one, I could still boot. My data is all on a pair of 120gb IDE drives, which are mirrored, and which have saved me from ugly restores, because I noticed that one disk had dropped out and I was able to just re-mirror without any major impact. John