RAIDZ capacity (was ZFS version 15 committed to head)
Marco van Lienen
marco+freebsd-current at lordsith.net
Sat Jul 17 14:41:49 UTC 2010
On Sat, Jul 17, 2010 at 01:04:52PM +0200, you (Stefan Bethke) sent the following to the -current list:
> > I have read many things about those differences, but why then does zfs on opensolaris report more available space whereas FreeBSD does not?
> > That would imply that my friend running osol build 117 couldn't fill up his raidz pool past the 3.56T.
> You didn't show us how your friends pool is set up.
> With RAIDZ1, the capacity of one of the devices in the pool is used for redundancy, with RAIDZ2 it's two disks worth. So three 2TB disks with RAIDZ1 gives you 4TB net capacity. If you don't care about redundancy, use a simple concatenation, i. e. don't specify mirror, raidz or raidz2 when creating the pool.
My friend created his raidz pool just the same way as I did: zpool create pool2 raidz c0d0 c0d1 c0d2
So just 3 dedicated drives.
I also posted the example of creating a test raidz pool based on 3 65Mb files.
On osol there is more available space being reported by 'zfs list' on that test raidz pool
When I created a similar test raidz pool also based on 3 65Mb files, 'zfs list' on my FreeBSD boxes (9.0-CURRENT amd64 and 8.0-RELEASE-p2 i386) is showing much less available space.
So regardless whether we use whole disks or simply files for testing purposes, 'zfs list' on the osol system is reporting more available space.
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