Date: Mon, 28 Jan 2013 12:06:17 +1030 From: Shane Ambler <FreeBSD@ShaneWare.Biz> To: james@mansionfamily.plus.com Cc: FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: Re: ZFS - whole disk or partition or BSD slice? Message-ID: <5105D611.4000506@ShaneWare.Biz> In-Reply-To: <5105BEE4.4030402@mansionfamily.plus.com> References: <5105BEE4.4030402@mansionfamily.plus.com>
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On 28/01/2013 10:27, james wrote: > I have a 9.1 system with some SATA disks in RAIDZ, upgraded from 9.0. > > The disks are all the same type, and I formatted them for FreeBSD and > put ZFS in a slice covering most of them. > > I have seen suggestions for OpenIndiana etc that it is better to let ZFS > have the whole raw disk and that this can control the way it manages the > disk writeback mode. > > Does this apply to FreeBSD and ZFS too? > > Presumably the disks are currently FreeBSD-specific. If I used raw > disks instead of slices, could I read them from a Solaris system too? I recall reading that using partitions for zfs on FreeBSD was as good as full disks. For a boot zpool we need to at least have a partition for the boot-code and one for zfs preventing the use of a full disk. ZFS is meant to be compatible between different endian systems (x86 and sparc) From what I have read and heard it sounds like zpools are expected be compatible between different OS's as well - as far as zpool versions are compatible - but I do expect it would depend on the partition tables being readable - while full disk usage should work I would also think GPT is compatible. OSX 10.5 (x86 and ppc) included a read-only zfs kext (before Apple canned the project) so it must have been able to read Solaris or FreeBSD created zpools which does indicate a fairly high level of compatibility. I believe the way ZFS marks disks/partitions with the zpool data is so that the zpools can be recognised between systems and controllers - it would be interesting to know if and under what conditions a zpool can be accessed, both between different FreeBSD machines as well as the possibility of reading on a Solaris/Indiana machine. Anyone have the resources to test?
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