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Chris mentioned "enough arms" and that's the key. If you have 8 or 10 or
12, that is not enough. You're gonna need arms, a whoooooole lotta arms
to out run an LTO tape! In an IBM class we were told "faster than two
LTO2 drives in parallel!" So I asked, on how many disk arms? IBM Said:
"Only 120 it's all we could spare at the time." Sure, like I got 120
arms on my average server.......
Chris also mentioned an ASP and that would be good too because now you
are reading from one set of arms and writing to another. Don't just
steal some disks from your current ASP though unless they are on a
separate RAID card and especially not if they are in the same RAID set!
This doesn't break any IBM i rules but it sure won't help performance of
the Virtual tape!!!
And WATCH your compression settings. TEST this because sometimes
compression will help (if you have plenty of CPU but fewer arms) and
sometimes it will hurt (if you have limited CPU but lots of arms.)
Remember that with Virtual Tape (and optical) the CPU does the
compression and with Tape the drive does it.
The virtual tape CANNOT be backed up while it is in use. The system
automatically flags all volumes of an image catalog that is mounted as
*ALWSAV *NO for this very reason.
Yeah don't try to MIMIX it to another system, that would be bad.
But Paul asked the really good question, why not back up at the remote
machine?
- Larry "DrFranken" Bolhuis
www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com
On 8/8/2013 5:09 PM, Sam_L wrote:
We backup just about everything to tape each night, including the IFS.
I would like to try backing up to a virtual tape, in the hope that it
will be significantly faster, and copy to a real tape during the day.
Does anyone have any "gotchas" or techniques to share?
Things that have come to mind are:
1) Disk space: We have more than enough.
2) We will need to exclude the virtual tape from the backup.
3) We are also running Mimix to a backup machine, so we need to exclude
the virtual tape from replication.
Thanks, Sam
midrange.com
