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Date:      Mon, 2 Apr 2012 22:39:15 +0400
From:      Sergey Kandaurov <pluknet@gmail.com>
To:        "bsalinux@gmail.com" <bsalinux@gmail.com>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: Swap on ZFS / swap_pager: indefinite wait buffer
Message-ID:  <CAE-mSOKqdT=-v9btkBrknuLXNEmmXHpLeHXLOTCcmV4u00toHQ@mail.gmail.com>
In-Reply-To: <CAB3Sx6f66QoT1jWY2eSxrB43X%2BSigTxEahTXL6ZGK8fFgSGHEQ@mail.gmail.com>
References:  <CAB3Sx6f66QoT1jWY2eSxrB43X%2BSigTxEahTXL6ZGK8fFgSGHEQ@mail.gmail.com>

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On 2 April 2012 22:13, bsalinux@gmail.com <bsalinux@gmail.com> wrote:
> Hi,
>
> I have been running FreeBSD 9.0-RELEASE from a USB stick running ZFS.
> I have created swap file on zfs volume using the md driver.
>
> Swapinfo shows
>
> Device =A0 =A0 =A0 =A0 =A01K-blocks =A0 =A0 Used =A0 =A0Avail Capacity
> /dev/md0 =A0 =A0 =A0 =A0 =A04194304 =A0 =A0 =A0 =A00 =A04194304 =A0 =A0 0=
%
>
>
> The system has hung twice and all I can find in the log is
>
> Mar 22 03:17:30 server kernel: swap_pager: indefinite wait buffer:
> bufobj: 0, blkno: 927, size: 4096
> Mar 23 09:00:26 server kernel: swap_pager: indefinite wait buffer:
> bufobj: 0, blkno: 55, size: 4096
> Mar 23 22:01:26 server kernel: swap_pager: indefinite wait buffer:
> bufobj: 0, blkno: 49, size: 4096
> Mar 24 04:00:38 server kernel: swap_pager: indefinite wait buffer:
> bufobj: 0, blkno: 60, size: 4096
>

That generally means that your storage is too slow (to handle swap).
See also FAQ:
http://www.freebsd.org/doc/en/books/faq/troubleshoot.html#INDEFINITE-WAIT-B=
UFFER

> As the swap is on zfs, I assume it is not failing.
>
> Do I need to move swap off of ZFS?
>

IIRC swap on ZFS is generally a bad idea.
Search web for bad stories.

--=20
wbr,
pluknet



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