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Date:      Sun, 19 May 2013 16:28:06 -0400
From:      Paul Kraus <>
To:        Dennis Glatting <>
Cc:        Tijl Coosemans <>,
Subject:   Re: More than 32 CPUs under 8.4-P
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <>

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On May 19, 2013, at 11:51 AM, Dennis Glatting <> wrote:

> ZFS hangs on multi-socket systems (Tyan, Supermicro) under 9.1. ZFS =
> not hang under 8.4. This (and one other 4 socket) is a production
> system.

	Can you be more specific, I have been running 9.0 and 9.1 =
systems with multi-CPU and all ZFS with no (CPU related*) issues.

* I say no CPU related issues because I have run into SATA timeout =
issues with an external SATA enclosure with 4 drives (I know, SATA port =
expanders are evil, but it is my best option here). Sometimes the zpool =
hangs hard, sometimes just becomes unresponsive for a while. My "fix", =
such as it is, is to tune the zfs per vdev queue depth as follows:


The defaults are 5 and 10 respectively, and when I run with those I have =
the timeout issues, but only under very heavy I/O load. I only generate =
such load when migrating large amounts of data, which thankfully does =
not happen all that often.

Paul Kraus
Deputy Technical Director, LoneStarCon 3
Sound Coordinator, Schenectady Light Opera Company

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