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From: "Stuart D. Gathman" <stuart@gathman.org>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Best way to run LVM over multiple SW RAIDs?
Date: Sat, 7 Dec 2019 18:14:05 -0500 (EST)	[thread overview]
Message-ID: <alpine.LRH.2.21.1912071804540.9108@fairfax.gathman.org> (raw)
In-Reply-To: <24044.11058.338208.602498@quad.stoffel.home>

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
play.)

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

  reply	other threads:[~2019-12-07 23:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29  8:47 [linux-lvm] Best way to run LVM over multiple SW RAIDs? Daniel Janzon
2019-12-07 16:16 ` Anatoly Pugachev
2019-12-07 17:37   ` Roberto Fastec
2019-12-07 20:34     ` Stuart D. Gathman
2019-12-07 22:44       ` John Stoffel
2019-12-07 23:14         ` Stuart D. Gathman [this message]
2019-12-08 11:57           ` Gionatan Danti
2019-12-08 22:51           ` John Stoffel
2019-12-09 10:40         ` Guoqing Jiang
2019-12-09 10:26 Daniel Janzon
2019-12-09 14:26 ` Marian Csontos
2019-12-10 11:23 ` Gionatan Danti
2019-12-10 21:29   ` John Stoffel
2019-12-16  8:22 Daniel Janzon

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