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Subject: Re: Urgently need some help solving lost space due to snapshots
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 <55C863DE.3000200@digiware.nl> <60563a3f.3d0a7128@fabiankeil.de>
From: Da Rock <freebsd-fs@herveybayaustralia.com.au>
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Date: Tue, 11 Aug 2015 20:19:14 +1000
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On 10/08/2015 20:34, Fabian Keil wrote:
> Willem Jan Withagen <wjw@digiware.nl> wrote:
>
>> On 10-8-2015 06:42, Da Rock wrote:
>>> I'm trying to move a pool from one system to another - exact same hdd
>>> and config, different in other areas. Both register same space
>>> available, and so should be no issue. The old system is quite full -
>>> still at least 5% free though.
>> Are the versions of your FreeBSD also equal?
>>
>> Because in newer version, the free space reservation is significantly
>> bigger. So if disks are equal size, then with newer FreeBSDs you have
>> less usable space available.
>> Don't know the exact SVN commit where it happened. But there are more
>> question on this topic in the list, and they all boil down to the same
>> thing: ZFS needs more reserved space to be able to do certain things
>> without freezing the system.
>>
>> I've not read any suggestions that you can circumvent this setting.
> You can increase the usable space by increasing vfs.zfs.spa_slop_shift:
>
> fk@r500 ~ $sysctl vfs.zfs.spa_slop_shift
> vfs.zfs.spa_slop_shift: 6
> fk@r500 ~ $zfs list tank
> NAME   USED  AVAIL  REFER  MOUNTPOINT
> tank   190G  34.4G   136K  /tank
> fk@r500 ~ $sudo sysctl vfs.zfs.spa_slop_shift=7
> vfs.zfs.spa_slop_shift: 6 -> 7
> fk@r500 ~ $zfs list tank
> NAME   USED  AVAIL  REFER  MOUNTPOINT
> tank   190G  36.2G   136K  /tank
>
> Fabian
What version is that on? I don't have the OID.