On Thu, Jan 17, 2008 at 11:57:39PM -0500, Patrick Zaloum wrote: > On Jan 17, 2008 11:33 PM, Andrew Sackville-West > <[EMAIL PROTECTED]> wrote: > > On Thu, Jan 17, 2008 at 10:48:25PM -0500, Damon L. Chesser wrote: > > > Andrew Sackville-West wrote: > > >> On Thu, Jan 17, 2008 at 02:55:41PM -0500, Patrick Zaloum wrote: > > >> > > >>> Hello! > > >>> I am planning on installing a new Etch server. What I would like is to > > >>> use 3xSATA2 disks to create a RAID5 array. During the install I know I > > ... snipped discussion of options... > OK So if i understand correctly, i should use software raid and not > onboard chipset raids.
well. you should use what *you* want to use. But given a choice between s/w raid or onboard chipset raid, *I* would choose (and have chosen) s/w raid for reasons already discussed. Given the choice between all three: s/w, separate h/w, or onboard h/w I'd take them in that order. But the distinction between s/w and separate h/w is a little smaller and for certain applications, the separate h/w may be better. It's reasonable to assume that if you don't know you need it, you probably don't. ;) > I should also not put the entire thing on raid5 > but rather raid1 for OS with one spare partition, and raid 5 for > data. yes. a raid 1 disk can be booted (ignoring certain hardware issues like some obscure disk driver. a good initrd should work around that fine) on any mobo as is. All you have to do is make sure you're MBR is copied onto all three disks as well. It gives really nice recovery if your "first" disk fails. For example, my array uses four disks with the first two partitions in RAID 1 for /boot and /. I've copied the MBR onto all four disks and can boot off any disk that the BIOS can see (two are on a separate card and BIOS can't see them, *but* I could swap cables and do it.) So basically, so long as a large truck doesn't run over the box, it will boot. Your raid 1 will come up degraded, but it will come up and you're running. > Is raid 5 really worth the effort with SATA software raid? Or should i > just use raid 1 all around.... you should read: http://www.miracleas.com/BAARF/ I've got the rest of my four disks in raid5. Its great for space, but I regret it. A couple times I've had an error hit a disk and when that thing starts trying to resync the disks, its awful. disk performance goes into the toilet. I'd not do that again and am trying to figure out how to get out of it right now. And one consideration, if you're resyncing a raid5 array and lose *another* disk (a real possibility, they work hard when resyncing) you are done. With raid 1 or raid 10 (mirrored, striped disks) you lose space but gain a little security. For example if I have 4 disks in raid 5 I get roughly 3/4 of the total size. But if I'm down one disk and am resyncing, if another disk fails, I lose the whole array. If I use those same 4 disks in raid 10 (two mirrors of two stripes or vice-versa, can't remember) I only get 1/2 the total space, but if I'm down a disk and resyncing, there's a 1 in 3 chance that I won't lose the array if another disk goes. (or something like that). If I run all 4 at raid1 then I would need to lose all 4 disks to lose the array. But I'd also only get 1/4 the total space. > Will the boot loader recognize a raid 1 root partition or will it give > me trouble? should give you no trouble at all. It looks just like a regular disk, for all practical purposes. Make sure you run through some failure scenarios before you start putting data on it. Test booting from different disks (actually remove disks and test it) and so forth so you have an understanding of how it works. And most importantly, remember that raid is *not* backup! A
signature.asc
Description: Digital signature
