Cynbe ru Taren wrote:
Just in case the RAID5 maintainers aren't aware of it:
The current Linux kernel RAID5 implementation is just
too fragile to be used for most of the applications
where it would be most useful.
In principle, RAID5 should allow construction of a
disk-based store which is considerably MORE reliable
than any individual drive.
In my experience, at least, using Linux RAID5 results
in a disk storage system which is considerably LESS
reliable than the underlying drives.
What happens repeatedly, at least in my experience over
a variety of boxes running a variety of 2.4 and 2.6
Linux kernel releases, is that any transient I/O problem
results in a critical mass of RAID5 drives being marked
'failed',
What kind of "transient io error" would that be?
That is not supposed to happen regularly. . .
You do replace failed drives immediately? Allowing
systems to run "for a while" in degraded mode is
surely a recipe for disaster. Degraded mode
has no safety at all, it is just raid-0 with a performance
overhead added in. :-/
Having hot spares is a nice way of replacing the failed
drive quickly.
at which point there is no longer any supported
way of retrieving the data on the RAID5 device, even
though the underlying drives are all fine, and the underlying
data on those drives almost certainly intact.
As other have showed - "mdadm" can reassemble your
broken raid - and it'll work well in those cases where
the underlying drives indeed are ok. It will fail
spectacularly if you have a real double fault though,
but then nothing short of raid-6 can save you.
Helge Hafting
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
