... but I have to ask.
How do I back this up?
Here is my definition of a backup :
(1) I can copy all data and metadata onto some media in
a manner that verifies the integrity of the data and
metadata written.
(1.1) By verify I mean that the data written onto
the media is read back and compared to the
source and accuracy is assured.
(2) I can walk away with the media and be able to restore
the data onto bare metal with nothing other than Solaris
10 Update 2 ( or Nevada ) CDROM sets and reasonable hardware.
I have a copy of the Solaris ZFS Administration Guide which is some
document numbered 817-2271. 158 pages and well worth printing out I think.
Let's suppose that I have a pile of disks arranged in mirrors and everything
seems to be going along swimmingly thus :
# zpool status zfs0
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
#
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
zfs0 95.3G 70.8G 27.5K /export/zfs
zfs0/backup 91.2G 70.8G 88.4G /export/zfs/backup
zfs0/backup/pasiphae 2.77G 24.2G 2.77G /export/zfs/backup/pasiphae
zfs0/lotus 786M 70.8G 786M /opt/lotus
zfs0/zone 3.40G 70.8G 24.5K /export/zfs/zone
zfs0/zone/common 24.5K 8.00G 24.5K legacy
zfs0/zone/domino 24.5K 70.8G 24.5K /opt/zone/domino
zfs0/zone/sugar 3.40G 12.6G 3.40G /opt/zone/sugar
At this point I attach a tape drive to the machine :
# devfsadm -v -C -c tape
devfsadm[24247]: verbose: symlink /dev/rmt/0 -
../../devices/[EMAIL PROTECTED],0/SUNW,[EMAIL PROTECTED],880/[EMAIL
PROTECTED],0:
.
.
.
devfsadm[24247]: verbose: symlink /dev/rmt/0ubn -
../../devices/[EMAIL PROTECTED],0/SUNW,[EMAIL PROTECTED],880/[EMAIL
PROTECTED],0:ubn
# mt -f /dev/rmt/0lbn status
DLT4000 tape drive:
sense key(0x6)= Unit Attention residual= 0 retries= 0
file no= 0 block no= 0
#
I then create a snapshot as per the documentation :
# zfs list zfs0
NAME USED AVAIL REFER MOUNTPOINT
zfs0 95.3G 70.8G 27.5K /export/zfs
# date
Tue Jun 27 18:10:36 EDT 2006
# zfs snapshot [EMAIL PROTECTED]
# zfs list
NAME USED AVAIL REFER MOUNTPOINT
zfs0 95.3G 70.8G 27.5K /export/zfs
[EMAIL PROTECTED] 0 - 27.5K -
zfs0/backup 91.2G 70.8G 88.4G /export/zfs/backup
zfs0/backup/pasiphae 2.77G 24.2G 2.77G /export/zfs/backup/pasiphae
zfs0/lotus 786M 70.8G 786M /opt/lotus
zfs0/zone 3.40G 70.8G 24.5K /export/zfs/zone
zfs0/zone/common 24.5K 8.00G 24.5K legacy
zfs0/zone/domino 24.5K 70.8G 24.5K /opt/zone/domino
zfs0/zone/sugar 3.40G 12.6G 3.40G /opt/zone/sugar
#
And then I send that snapshot to tape :
# zfs send [EMAIL PROTECTED] /dev/rmt/0mbn
#
That command ran for maybe 15 seconds. I seriously doubt that 95GB of data
was written to tape and verified in that time although I'd like to see the
device and bus that can do it! :-)
I'll destroy that snapshot and try something else here :
# zfs destroy [EMAIL PROTECTED]
Now perhaps the mystery is to try a different ZFS filesystem :
# date
Tue Jun 27 18:17:33 EDT 2006
# zfs snapshot zfs0/[EMAIL PROTECTED]:17Hrs
I'll check the tape drive that did something above although I have no idea
what.
# mt -f /dev/rmt/0mbn status
DLT4000 tape drive:
sense key(0x0)= No Additional Sense residual= 0 retries= 0
file no= 1 block no= 0
#
Now I will send that stream to the tape :
# zfs send zfs0/[EMAIL PROTECTED]:17Hrs /dev/rmt/0mbn
The tape is now doing something again and I don't know what.
I would like to think that when it is down I can walk to a totally new
machine and restore the ZFS filesystem zfs0/lotus with no issue but I don't
see a verify step here anywhere and I really have no idea what will happen
when I hit the end of that tape.
I am very bothered that my 95GB zfs0 did not go to tape and I don't know why
not. I think that my itty bitty 786MB zfs0/lotus is actually going to tape
right now ( lights are flashing )
