As near as I can tell the ZFS filesystem has no way to backup easily to a
tape in the same way that ufsdump has served for years and years.
Here is what I just tried :
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
zfs0 100G 65.8G 27.5K /export/zfs
zfs0/backup 96.2G 65.8G 93.4G /export/zfs/backup
zfs0/backup/pasiphae 2.77G 24.2G 2.77G /export/zfs/backup/pasiphae
zfs0/lotus 786M 65.8G 786M /opt/lotus
zfs0/zone 3.40G 65.8G 24.5K /export/zfs/zone
zfs0/zone/common 24.5K 8.00G 24.5K legacy
zfs0/zone/domino 24.5K 65.8G 24.5K /opt/zone/domino
zfs0/zone/sugar 3.40G 12.6G 3.40G /opt/zone/sugar
# date
Thu Jul 6 19:00:33 EDT 2006
# zfs snapshot zfs0/[EMAIL PROTECTED]
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
zfs0 100G 65.8G 27.5K /export/zfs
zfs0/backup 96.2G 65.8G 93.4G /export/zfs/backup
zfs0/[EMAIL PROTECTED] 0 - 93.4G -
zfs0/backup/pasiphae 2.77G 24.2G 2.77G /export/zfs/backup/pasiphae
zfs0/lotus 786M 65.8G 786M /opt/lotus
zfs0/zone 3.40G 65.8G 24.5K /export/zfs/zone
zfs0/zone/common 24.5K 8.00G 24.5K legacy
zfs0/zone/domino 24.5K 65.8G 24.5K /opt/zone/domino
zfs0/zone/sugar 3.40G 12.6G 3.40G /opt/zone/sugar
# mt -f /dev/rmt/0cbn status
HP DAT-72 tape drive:
sense key(0x0)= No Additional Sense residual= 0 retries= 0
file no= 0 block no= 0
# zfs send zfs0/[EMAIL PROTECTED] > /dev/rmt/0cbn
cannot write stream: I/O error
#
Of course it took a number of hours for that I/O error to appear because the
tape hit its capacity. There were no reports of 10% or 20% and no prompt
for "end of media" and "please insert a blank tape and hit enter when ready"
sort of thing.
This ZFS filesystem is now in production. I think that someone had better
step up to the plate and suggest the method by which people are supposed to
do a backup.
I gave this some thought and the best that I can come with is this :
(1) perhaps I can break my ZFS filesystem area into chunks that fit on
a HP DAT-72 tape drive without compression. I think this is just
not reasonable.
(2) perhaps I can use find and tar or cpio to backup small "tape drive
capacity" sized chunks of the ZFS filesystem. Then dump these with
some hand written notes or post-it notes to indicate what directory
bits I have and what tape is needed to get the other bits. Let me
expound on this a tad :
(2.1) I have the following directories in my ZFS filesystem that
is called "zfs0/backup" :
Blastwave OpenSolaris MicroSoft Sun-software mars
jupiter pasiphae jumpstart Sol-2.5.1 open-sources
I can check the sizes of each of these and see that they all
fit into my tape drive as separate little tar dumps.
i.e.:
$ du -sk OpenSolaris
21466143 OpenSolaris
However I will quickly end up with a pile of tapes to dump
one ZFS filesystem and no easy way to get incrementals
other than to 'touch timestamp' and then use find to build
a list of new or modified files based on the -newer switch.
I can not use incremental snapshots because I was not able
to dump the snapshot in the first place. Serves me no use.
The benefit here, if any, is that I can at least use Jorg
Schillings star to get POSIX compliant dumps. That is if
I can rest assured that all ZFS metadata is backed up also.
I am not sure on that yet. :-(
(2.2) Use Samba to share out the whole filesystem tree and then
backup with Veritas NetBackup on a Microsoft Windows server.
(3) Attach a single large 300GB or larger sized disk somehow and then
use ZFS send/receive to get the data onto a UFS based filesystem
and then use ufsdump. No, this will not work because ZFS send
and receive will only allow me to go from one ZFS filesystem to
another. I still have no tape backup.
(4) Never backup.
Really, I'm not happy here.
I am more than able to read the ZFS Administration Guide and read the man
pages but I just don't see a manner to backup my ZFS filesystem to tape.
So here I sit with this :
$ zpool status -v
pool: zfs0
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
zfs0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t10d0 ONLINE 0 0 0
c1t10d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t11d0 ONLINE 0 0 0
c1t11d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t12d0 ONLINE 0 0 0
c1t12d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t9d0 ONLINE 0 0 0
c1t9d0 ONLINE 0 0 0
mirror ONLINE 0 0 0
c0t13d0 ONLINE 0 0 0
c1t13d0 ONLINE 0 0 0
errors: No known data errors
... with no way to back it up to tape ?
Someone please enlighten me.
Dennis Clarke
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