Date: Fri, 3 Feb 2012 10:47:21 -0500 From: "David Magda" <dmagda@ee.ryerson.ca> To: "Pete French" <petefrench@ingresso.co.uk> Cc: freebsd-stable@freebsd.org Subject: Re: Sector size of a zvol Message-ID: <01775b9823b5bacb14d03315a6321d61.squirrel@webmail.ee.ryerson.ca> In-Reply-To: <E1RtKfv-000BKF-4L@dilbert.ingresso.co.uk> References: <E1RtKfv-000BKF-4L@dilbert.ingresso.co.uk>
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On Fri, February 3, 2012 10:03, Pete French wrote:
> [...] But what I am talking about is the sector size
> presneted by the 'fake' disc that a ZVOL creates - that always seems
> to be 512 bytes, despite the fact that the zvol blocksize is 8k. Seems
> odd to me (and that 8k size os alterable, but just doesnt seem to
> be reflected in the zvol). As it stands I can make a zpool on top
> of 4k discs, a ZVOL using 8k blocks on top of that, but the things
> talking to it will use 512 byte chunks, which surely impacts performance ?
Try the following from the zfs(1M) man page:
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
[...]
-b blocksize
Equivalent to -o volblocksize=blocksize. If this option is
specified in conjunction with -o volblocksize, the resulting
behavior is undefined.
http://www.freebsd.org/cgi/man.cgi?query=zfs
Did use "blocksize" or "volblocksize" in your "zfs create" command?
A thread for zfs-discus on "volblocksize":
http://mail.opensolaris.org/pipermail/zfs-discuss/2005-November/000450.html
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