Urgently need some help solving lost space due to snapshots during receive op

[Fabian Keil]

Da Rock <freebsd-fs at herveybayaustralia.com.au> wrote:

> On 10/08/2015 20:34, Fabian Keil wrote:
> > Willem Jan Withagen <wjw at 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 at r500 ~ $sysctl vfs.zfs.spa_slop_shift
> > vfs.zfs.spa_slop_shift: 6
> > fk at r500 ~ $zfs list tank
> > NAME   USED  AVAIL  REFER  MOUNTPOINT
> > tank   190G  34.4G   136K  /tank
> > fk at r500 ~ $sudo sysctl vfs.zfs.spa_slop_shift=7
> > vfs.zfs.spa_slop_shift: 6 -> 7
> > fk at r500 ~ $zfs list tank
> > NAME   USED  AVAIL  REFER  MOUNTPOINT
> > tank   190G  36.2G   136K  /tank

> What version is that on? I don't have the OID.

It's available in 11-CURRENT (obviously), 10-STABLE and will be
in the 10.2 release:
https://svnweb.freebsd.org/base?view=revision&revision=275490

Fabian
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