Date: Sat, 20 Feb 2010 13:25:54 +0100 From: Dimitry Andric <dimitry@andric.com> To: mailinglists <mailinglists@debank.tv> Cc: freebsd-fs@freebsd.org Subject: Re: zfs on 4k sector disks Message-ID: <4B7FD4D2.7040802@andric.com> In-Reply-To: <e7531071831ef4c088902a8b5fe94dab,4B7FAF99.10308@debank.tv> References: <e7531071831ef4c088902a8b5fe94dab,4B7FAF99.10308@debank.tv>
next in thread | previous in thread | raw e-mail | index | archive | help
On 2010-02-20 10:47, mailinglists wrote: > This "Advanced Format" basically means the sectors size on disk is > changed to 4k in stead of 512k. Please note those disks still seem to expose 512B sectors to any OS; the 4kiB sectors are only used internally. And there seems to be no jumper to "fix" this behaviour... Unaligned writes can cause multiple read-write-modify operations, which are most likely bad for performance. > I'm wondering if freeBSD 8.0 using ZFS raidz and drives like these will > work properly, I've seen a lot of articles and postings about partitions > not being properly aligned with the physical disk layout and suffering > big performance hits. My question is; should I worry about these issues > or does ZFS already align the data on a 4k border? You can at least try to make sure your partitions are aligned to 4kiB. This should be easy enough to do with e.g. gpart(8). I see no specific alignment options in the zpool(1M) or zfs(1M) manpages, but there may be some trick that I am not aware of. :) With UFS, you might want to experiment with block and fragment sizes, to see what is most optimal. For example, a block size of 32kiB and fragment size of 4kiB, on a partition aligned to 4kiB.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4B7FD4D2.7040802>