Date: Mon, 28 Jan 2013 11:10:04 -0500 From: Paul Kraus <paul@kraus-haus.org> To: FreeBSD Mailing List <freebsd-questions@freebsd.org> Subject: Re: ZFS - whole disk or partition or BSD slice? Message-ID: <7D460604-8F6B-454F-B717-678F64A75062@kraus-haus.org> In-Reply-To: <5105D611.4000506@ShaneWare.Biz> References: <5105BEE4.4030402@mansionfamily.plus.com> <5105D611.4000506@ShaneWare.Biz>
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On Jan 27, 2013, at 8:36 PM, Shane Ambler wrote: > 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. I have been using ZFS with GPT partitions with no issues. I have = NOT compared performance between whole disk and partitioned, which is = where the difference in Solaris arises (ZFS makes better use of the = physical drive's write cache). > ZFS is meant to be compatible between different endian systems (x86 = and sparc) =46rom 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. The target OS must be able to read the partitioning scheme used. = I am not aware of Solaris / OpenSolaris / Illumos being able to read GPT = partitions, but it has been over 6 months since I played with any of = them. > 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? When you give ZFS the whole disk, it writes an EFI-like label on = the drive and makes us of one partition for the ZFS data. So there *is* = a form of partitioning at the lower most layer, it is just *not* user = managed partitioning. -- Paul Kraus Deputy Technical Director, LoneStarCon 3 Sound Coordinator, Schenectady Light Opera Company
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