Adam Thornton wrote:
On Jul 18, 2008, at 10:49 AM, David Kreuter wrote:
client 1. quiesces the DB of bunches of oracle machines with SQL
statements. Sync;sync the linux fs so we're sure we're committed to
disk. CMS server flashcopies all (ALL) of the mdisks of the linux
machines.
Uhhhhh,,,,unless you're unmounting them first, this isn't really
safe. You know that, right? Your Oracle backups are probably OK
(since you're explicitly halting IO and you're flushing the disks
first, so although the FS is dirty there's really little chance of it
ACTUALLY being corrupt), but your system images aren't.
There was a very lengthy discussion aboout this a while ago (maybe a
year or two), and as I recall there is no safe way to do it external to
the guest.
Since then, I've read of folk in Toyland suspending their xen guests,
copying the system and then restoring them to operation, without
dropping a TCP connexion. I guess they weren't using the kind of desktop
I have to live with;-)
It seems the copy of the saved system starts just fine, as you'd expect.
I don't recall anyone said it was a bad idea.
Client 2 is a much better idea.
Now, if you can arrange to UNMOUNT the fses you care about on client
1, you'd be fine. But that probably requires out-and-out stopping
Oracle rather than just quiescing it, so no process has open files on
the volume.
If you can't do that, I'd do the client 1 thing, and then mount the
snapshot volumes r/o, fsck 'em, and then back those up with a file-
backup utility.
Seems to me you might as well shut the system down and be done with it.
What's the diffetence in elapsed time? Seconds? Tens of minutes?
--
Cheers
John
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