how to access ZFS snapshot via iSCSI

[Gezeala M. Bacuño II]

On Wed, Sep 26, 2012 at 7:37 AM, Zeus Panchenko <zeus at ibs.dn.ua> wrote:
> hi all,
>
> please, may somebody advice, can I access ZFS snapshot via iSCSI?
>
> I do can get access to ZFS filesystem and zvol, but how to access ZFS snapshot?
>
> I am trying that via istgt, in istgt.conf I put:
>
> [LogicalUnit4]
>   Comment "ZVOL 500Gb to test"
>   TargetName zvol-totest
>   Mapping PortalGroup1 InitiatorGroup1
>   AuthMethod Auto
>   AuthGroup AuthGroup1
>   UseDigest Auto
>   UnitType Disk
>   QueueDepth 64
>   LUN0 Storage /dev/zvol/storage/win/zvol-totest Auto
>
> and I can mount it and use
>
> when I put
>
> [LogicalUnit5]
>   Comment "snapshot of ZVOL 500Gb totest"
>   TargetName zvol-totest-snapshot
>   Mapping PortalGroup1 InitiatorGroup1
>   AuthMethod Auto
>   AuthGroup AuthGroup1
>   UseDigest Auto
>   UnitType Disk
>   QueueDepth 64
>   LUN0 Storage /dev/zvol/storage/win/zvol-totest at hourly-2012-09-26-11 Auto
>
> and trying to restart istgt, I'm getting:
>
> LU4 HDD UNIT
> LU4: LUN0 file=/dev/zvol/storage/win/zvol-totest, size=536870912000
> LU4: LUN0 1048576000 blocks, 512 bytes/block
> LU4: LUN0 500.0GB storage for iqn.2007-09.jp.ne.peach.istgt:zvol-totest
> LU4: LUN0 serial 10000004
> LU4: LUN0 read cache enabled, write cache enabled
> LU4: LUN0 command queuing enabled, depth 64
> LU5 HDD UNIT
> LU5: LUN0 file=/dev/zvol/storage/win/zvol-totest at hourly-2012-09-26-11, size=536870912000
> LU5: LUN0 1048576000 blocks, 512 bytes/block
> istgt_lu_disk.c: 642:istgt_lu_disk_init: ***ERROR*** LU5: LUN0: open error(errno=17)
> istgt_lu.c:2091:istgt_lu_init_unit: ***ERROR*** LU5: lu_disk_init() failed
> istgt_lu.c:2166:istgt_lu_init: ***ERROR*** LU5: lu_init_unit() failed
> istgt.c:2799:main: ***ERROR*** istgt_lu_init() failed
> /usr/local/etc/rc.d/istgt: WARNING: failed to start istgt
>
>
> where am I wrong?
>
> --
> Zeus V. Panchenko                               jid:zeus at im.ibs.dn.ua
> IT Dpt., I.B.S. LLC                                       GMT+2 (EET)
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you should clone the snapshot first:
zfs clone dev/zvol/storage/win/zvol-totest at hourly-2012-09-26-11
dev/zvol/storage/win/zvol-totest-clone

then on istgt.conf
> [LogicalUnit5]
>   Comment "snapshot of ZVOL 500Gb totest"
>   TargetName zvol-totest-snapshot
>   Mapping PortalGroup1 InitiatorGroup1
>   AuthMethod Auto
>   AuthGroup AuthGroup1
>   UseDigest Auto
>   UnitType Disk
>   QueueDepth 64
LUN0 Storage dev/zvol/storage/win/zvol-totest-clone Auto