Re: Backup to Virtual Tape

[Sam_L <lennon_s_j@xxxxxxxxxxx>]

I worry about contention, others on the staff think "disk to disk" has 
to be faster.  We have 12 units, which I equate to 12 arms, raid 5, 
about 1 TB I believe, not hurting for disk space.

I will have to try it...  An yes, experiment with a few libraries and 
IFS directories.  And check out what compression does to it.

Good to know the virtual tape is automatically excluded from a save.

Backup on the remote machine is currently impractical.  It is 900+ miles 
away and the prospect of local restores, which we occasionally do, would 
be difficult and slower.  And the MLB is on the production box.

Thanks,

Sam

On 8/8/2013 5:55 PM, DrFranken wrote:
> 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