On 11/13/22 13:02, hw wrote:
On Fri, 2022-11-11 at 07:55 -0500, Dan Ritter wrote:
hw wrote:
On Thu, 2022-11-10 at 20:32 -0500, Dan Ritter wrote:
Linux-Fan wrote:
[...]
* RAID 5 and 6 restoration incurs additional stress on the other
disks in the RAID which makes it more likely that one of them
will fail. The advantage of RAID 6 is that it can then recover
from that...
Disks are always being stressed when used, and they're being stessed as well
when other types of RAID arrays than 5 or 6 are being rebuild. And is there
evidence that disks fail *because* RAID arrays are being rebuild or would
they
have failed anyway when stressed?
Does it matter? The observed fact is that some notable
proportion of RAID 5/6 rebuilds fail because another drive in
that group has failed.
Fortunately, I haven't observed that. And why would only RAID 5 or 6 be
affected and not RAID 1 or other levels?
Any RAID level can suffer additional disk failures while recovering from
a disk failure. I saw this exact scenario on my SOHO server in August
2022. The machine has a stripe of two mirrors of two HDD's each (e.g.
ZFS equivalent of RAID10). One disk was dying, so I replaced it. While
the replacement disk was resilvering, a disk in the other mirror started
dying. I let the first resilver finish, then replaced the second disk.
Thankfully, no more disks failed. I got lucky.
David
