Date: Fri, 03 Feb 2012 16:42:43 +0000 From: Pete French <petefrench@ingresso.co.uk> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/164741: zvol always present as 512 bytes/sector regardless of blocksize Message-ID: <E1RtMDj-0000tj-T2@dilbert.ingresso.co.uk> Resent-Message-ID: <201202031650.q13Go9Yf076960@freefall.freebsd.org>
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>Number: 164741
>Category: kern
>Synopsis: zvol always present as 512 bytes/sector regardless of blocksize
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Feb 03 16:50:09 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Pete French
>Release: FreeBSD 8.2-STABLE amd64
>Organization:
Ingresso Ltd
>Environment:
System: FreeBSD dilbert.london-internal.ingresso.co.uk 8.2-STABLE FreeBSD 8.2-STABLE #0: Fri Jan 6 12:44:04 GMT 2012 petefrench@dilbert.london-internal.ingresso.co.uk:/usr/obj/usr/src/sys/GENERIC amd64
>Description:
A zvol may be created with a specific sectorsize, specified with -b
or the volblocksize property. The resulting device in /dev/zvol
always appears to have 512 bytes per sector however, as reported by
diskinfo
>How-To-Repeat:
# zfs create -V 1G -b 512 tank/test1
# zfs create -V 1G -b 4k tank/test2
# zfs create -V 1G tank/test3
# zfs get volblocksize tank/test1 tank/test2 tank/test3
NAME PROPERTY VALUE SOURCE
tank/test1 volblocksize 512 -
tank/test2 volblocksize 4K -
tank/test3 volblocksize 8K -
# diskinfo /dev/zvol/tank/test*
/dev/zvol/tank/test1 512 1073741824 2097152 0 0
/dev/zvol/tank/test2 512 1073741824 2097152 0 0
/dev/zvol/tank/test3 512 1073741824 2097152 0 0
>Fix:
For zvols to be uses as iscsi devices the desired blocksize can
be specified in the istgt config file. For volumes being used
internally however (e.g. as volumed for VirtualBox machines)
I have discovered no workaround.
>Release-Note:
>Audit-Trail:
>Unformatted:
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