Ruslan Sivak spake the following on 5/7/2007 1:44 PM:
Toby Bluhm wrote:
Ruslan Sivak wrote:
Ross S. W. Walker wrote:
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Ruslan Sivak Sent: Monday, May 07, 2007 12:53 PM To: CentOS mailing list Subject: [CentOS] Anaconda doesn't support raid10
So after troubleshooting this for about a week, I was finally able to create a raid 10 device by installing the system, copying the md modules onto a floppy, and loading the raid10 module during the install. Now the problem is that I can't get it to show up in anaconda. It detects the other arrays (raid0 and raid1) fine, but the raid10 array won't show up. Looking through the logs (Alt-F3), I see the following warning:
WARNING: raid level RAID10 not supported, skipping md10. I'm starting to hate the installer more and more. Why won't it let me install on this device, even though it's working perfectly from the shell? Why am I the only one having this problem? Is nobody out there using md based raid10?
Most people install the OS on a 2 disk raid1, then create a separate raid10 for data storage.
Anaconda was never designed to create RAID5/RAID10 during install.
-Ross
Whether or not it was designed to create a Raid5/raid10, it allows the creating of raid5 and raid6 during install. It doesn't, however, allow the use of raid10 even if it's created in the shell outside of anaconda (or if you have an old installation on a raid10). I've just installed the system as follows
Raid1 for /boot with 2 spares (200mb) raid0 for swap (1GB) raid6 for / (10GB)
after installing, I was able to create a raid10 device and successfully mount and automount by using /etc/fstab
Now to test what happens when a drive fails. I pulled out the first drive - Box refuses to boot. Going into rescue mode, I was able to mount /boot, was not able to mount the swap drive (as to be expected, as it's a raid0), was also not able to mount the / for some reason, which is a little surprising. I was able to mount the raid10 parition just fine. Maybe I messed up somewhere along the line. I'll try again, but it's disheartening to see that a raid6 array would die after one drive failure, even if it was somehow my fault. Also assuming that the raid5 array could be recovered, what would I do with the swap partition? Would I just recreate it from the space in the leftover drives and would that be all that I need to boot? Russ
Russ,
Nothing here to help you (again - :) just looking down the road a little. If you do get this thing working the way you want, will you be able to trust it to stay that way?
Well, it's been my experience, that in linux, unlike windows, it might take a while to get things the way you want, but once you do, you can pretty much trust it to stay that way. So yea, this is what I'm looking to do here. I want to set up a system, that will live after 1 (or possibly 2) drive failures. I want to know what I need to do ahead of time, so that I can be confident in my set up, and know what to do in case disaster strikes.
Russ
If you have the hardware, or the money, you can make a system pretty durable. But you get to a point that the gains aren't worth the cost. You can get a system to 3 "9's" fairly easy, but the cost to get to 4 "9's" is much more. If you want something better than 4 "9's", you will have to look at clustering, because a single reboot in a month can shoot down your numbers.
If you want total reliability, you will need hot spares and a raid method that builds quickly, and you will need regular backups.