Certainly that is where the phrase 'backup' comes from. If you want integrity you can count on, stop transactions to the RAID subsystem, make a tape/dvd/etc, then fail/replace your drives, if it works you smile. If ever it stops working, replace the rest of the drives and recover from tape/dvd/etc. There is no way to guarantee that the RAID will save your tushy. Just last week I spent a couple hours building a new system with simple RAID 1 on the boot & root. I actually followed a manual step by step to make sure I did it right (not always my style=). Two ugly experiences were that when I 'tested' by unplugging a disk & boot, the system would not boot 'normally' - it wanted be to go hand type some disk node that supposedly I should know about that it wanted I guess. OK, so I plug in the drive and all is normal. I download and install mindi/mondo and make a bootable CD since Microlite BackupEDGE does not handle RedHat software RAID, and simply reboot the system with the CD in place. The CD timed out and launched from the console message and destroyed my system with the same message as when I removed one disk. Given this, I am abandoning the beauty of RAID on my root/boot disk. I will recover from DVD if (read when) it fails. Moral of the story is: DON'T EVER COUNT ON RAID to save your hide. Bill Watson [EMAIL PROTECTED]
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ahmed Kamal Sent: Thursday, May 01, 2008 11:35 AM To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list Subject: [rhelv5-list] Replacing disks under 3ware-9550SX safely Hello, I'm working on a server with a 3w-9550SX controller, with 3x500G disks in a raid-5 and 1x500G hot spare. One night, a disk fails, and the server crashes! Working on the server, I see that many filesystems were destroyed beyond repair!! This was too bad to hear. Some LVM volumes were repaired, others were restored from backup. The bad disk was removed. I learnt that 3ware controllers aren't really high quality, and they probably corrupt the FSs. Since all disks are same age, I thought I'd buy new disks to replace the old ones. I bought 4x500G barracuda-ES drives, which should be high quality. Here lies my problem. I need to replace the 3 running disks, with 3 new disks, and add an extra one as hot spare. I am scared to do that, because the standard way is to "fail" a disk, and rebuild on a new one, then repeat for the other 2 disks till all 3 are replaced. Now this puts me in a vulnerable situation, if I "fail" a disk, and while rebuilding another disk naturally fails, all data is gone! Is there any other "wise" way to do what I want safely ? I contacted 3w support, and they just insist I should fail/rebuild, but since I don't have much faith in their controllers or the old disks ... any smarter way to do this ? Regards
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