[linux-lvm] Best way to run LVM over multiple SW RAIDs?

Stuart D. Gathman stuart at gathman.org
Sat Dec 7 23:14:05 UTC 2019

On Sat, 7 Dec 2019, John Stoffel wrote:

> The biggest harm to performance here is really the RAID5, and if you
> can instead move to RAID 10 (mirror then stripe across mirrors) then
> you should be a performance boost.

Yeah, That's what I do.  RAID10, and use LVM to join together as JBOD.
I forgot about the raid 5 bottleneck part, sorry.

> As Daniel says, he's got lots of disk load, but plenty of CPU, so the
> single thread for RAID5 is a big bottleneck.

> I assume he wants to use LVM so he can create volume(s) larger than
> individual RAID5 volumes, so in that case, I'd probably just build a
> regular non-striped LVM VG holding all your RAID5 disks.  Hopefully

Wait, that's what I suggested!

> If you can, I'd get more SSDs and move to RAID1+0 (RAID10) instead,
> though you do have the problem where a double disk failure could kill
> your data if it happens to both halves of a mirror.

No worse than raid5.  In fact, better because the 2nd fault always
kills the raid5, but only has a 33% or less chance of killing the
raid10.  (And in either case, it is usually just specific sectors,
not the entire drive, and other manual recovery techniques can come into

 	      Stuart D. Gathman <stuart at gathman.org>
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

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