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Date:      Thu, 18 Oct 2012 16:31:52 -0500
From:      Dustin Wenz <dustinwenz@ebureau.com>
To:        Steven Hartland <killing@multiplay.co.uk>
Cc:        freebsd-fs@freebsd.org, Mark Felder <feld@feld.me>
Subject:   Re: Imposing ZFS latency limits
Message-ID:  <DE407287-F339-4F92-9CE3-A32804E6EAE2@ebureau.com>
In-Reply-To: <8C42CB56F50F4D8AB949BDD91970D388@multiplay.co.uk>
References:  <8C42CB56F50F4D8AB949BDD91970D388@multiplay.co.uk>

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The way I can usually detect this is by watching the operation queues =
with gstat. If a disk is running slower than the others, I/O ops tend to =
pile up. When that happens, I can restore performance by taking the disk =
offline. It's a manual process; I think the filesystem should do better =
than that.

	- .Dustin

On Oct 17, 2012, at 8:38 AM, Steven Hartland <killing@multiplay.co.uk> =
wrote:

> ----- Original Message ----- From: "Mark Felder" <feld@feld.me>
>> On Tue, 16 Oct 2012 06:25:57 -0500, Olivier Smedts <olivier@gid0.org> =
 wrote:
>>>=20
>>> That would be great - no need for TLER drives. But if you want to
>>> "drop" the drive from the bus, that would be a GEOM thing. Don't =
know
>>> if that's possible to implement.
>> This would be GREATLY appreciated. I've seen this happen on my own =
ZFS  boxes as well as on a custom made SAN. It's painful but easy to =
detect  when you notice the symptoms...
>=20
> Interesting, what metrics where you using which made it easy to =
detect,
> work be nice to know your process there Mark?
>=20
>   Regards
>   Steve
>=20
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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>=20




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