On Oct 25, 2009, at 1:45 AM, Orvar Korvar wrote:
I am trying to backup a large zfs file system to two different
identical hard drives. I have therefore started two commands to
backup "myfs" and when they have finished, I will backup "nextfs"
zfs send mypool/m...@now | zfs receive backupzpool1/now & zfs send
mypool/m...@now | zfs receive backupzpool2/now ; zfs send mypool/
nex...@now | zfs receive backupzpool3/now
in parallell. The logic is that the same file data is cached and
therefore easy to send to each backup drive.
Should I instead have done one "zfs send..." and waited for it to
complete, and then started the next?
Parallel works, well, in parallel. Unless the changes are in the ARC,
you
will be spending a lot of time waiting on disk. So having multiple
sends in
parallel, in general, gains parallelism. If you only have a single
HDD, you
might not notice much improvement, though.
It seems that "zfs send..." takes quite some time? 300GB takes 10
hours, this far. And I have in total 3TB to backup. This means it
will take 100 hours. Is this normal? If I had 30TB to back up, it
would take 1000 hours, which is more than a month. Can I speed this
up?
CR 6418042 integrated in b102 and Solaris 10 10/09 improves send
performance.
Is rsync faster? As I have understood it, "zfs send.." gives me an
exact replica, whereas rsync doesnt necessary do that, maybe the ACL
are not replicated, etc. Is this correct about rsync vs "zfs send"?
I general, rsync will be slower, especially if there are millions of
files, because it
must stat() every file to determine those that have changed.
-- richard
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
