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Date: Wed, 17 Jul 2013 13:38:01 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: freebsd-stable@FreeBSD.org, freebsd-fs@FreeBSD.org
Subject: Re: Shutdown problem with an USB memory stick as ZFS cache device
References: <51E6555D.2080803@cloverinformatica.it>
 <op.w0c1l8yp8527sy@ronaldradial.versatec.local>
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on 17/07/2013 12:50 Ronald Klop said the following:
> Does sysctl hw.usb.no_shutdown_wait=1 help?

I believe that the root cause of the issue is that ZFS does not perform full
clean up on shutdown and thus does not release its devices.  But perhaps I am
mistaken.
In any case, I think that doing the same kind of clean up as done on zfs module
unload would be advantageous.

-- 
Andriy Gapon