Date: Sat, 23 Oct 2010 10:58:32 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: "Eugene M. Kim" <gene@nttmcl.com> Cc: fs@freebsd.org Subject: Re: ZFS: Parallel I/O to vdevs that appear to be separate physical disks but really are partitions Message-ID: <20101023085832.GD1742@garage.freebsd.pl> In-Reply-To: <4CC215B4.3050607@nttmcl.com> References: <4CC215B4.3050607@nttmcl.com>
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[-- Attachment #1 --] On Fri, Oct 22, 2010 at 03:52:36PM -0700, Eugene M. Kim wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Greetings, > > I run a FreeBSD guest in VMware ESXi with a 10GB zpool. Lately the > originally provisioned 10GB proved insufficient, and I would like to > provision another 10GB virtual disk and add it to the zpool as a > top-level vdev. > > The original and new virtual disks are from the same physical pool (a > RAID-5 array), but appears to be separate physical disks to the > FreeBSD guest (da0 and da1). I am afraid that the ZFS would schedule > I/O to the two virtual disks in parallel thinking that the pool > performance will improve, while the performance would actually suffer > due to seeking back and forth between two regions of one physical pool. > > 1. Will ZFS schedule parallel access to different top-level vdevs? Yes, ZFS stripes requests over all top level vdevs. > 2. If so, how can I suggest ZFS that certain vdevs should be treated > not as separate physical disks but as partitions on the same physical > disk? Nope, that's not possible. Instead of adding next 10GB disk maybe it is possible to grow the one you have? ZFS should be able to grow automatically. -- Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkzCo7cACgkQForvXbEpPzT/YACcDq6bxtlR7oLaRFUZeaQ5nDzM X9gAoK36XBJcZsabNBwbKn8+I06l367T =RNLw -----END PGP SIGNATURE-----
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