Re: else or Debian (Re: ZFS performance (was: Re: deduplicating file systems: VDO with Debian?))
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?
> The drives were likely to be from the
> same cohort of the manufacturer, and to have experienced very
> similar read/write activity over their lifetime.
Yes, and that means that might they fail all at about the same time due to age
and not because an array is being rebuild.
The question remains what the ratio between surviving volumes and lost volumes
is.
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