Some more snippets from the best practices guide...!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It works as follows
1. Initially a 5 GB area is allocated on LUN.
2. When the backup software fills the initial 5 GB, the disk library
allocates another 5 GB area. The new area might be on a different LUN.
3. The disk library software will continue allocating 5 GB pieces in this
way untill the total maximum capacity of the emulated tape is reached.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I hope this clarifies.
Regards,
PP BIJU KRISHNAN
On 9/7/06, Veritas Netbackup <backupicici at gmail.com> wrote:
>
> Yes Paul,
>
> My privlege, the following section shd suffice, though I can mail u the
> entire doc offline {Pls let me know}.
> Its the CDL Admin guide available from EMC powerlink that describes, and I
> had got some inputs from the EMC support engineer.
>
> ===========================================================
> The Tape Capacity On Demand feature allows you to allocate a small
> amount of space when you create your virtual tapes, and later
> automatically allocate additional space as needed. If you do not use
> this option, the Disk Library server will allocate each virtual tape at
> the full size of that tape. You can enable Tape Capacity On Demand
> only while creating a virtual tape library or virtual tape drive. The
> Tape Capacity On Demand for virtual tape libraries or drives is
> enabled by default.
> The Tape Capacity On Demand feature will appear only if you have
> enabled the Advanced Tape Creation method.
> ===========================================================
>
> I too am confused as to whether I'm looking at the right direction, and
> yes increasing the MPX level seems to the only solution now.
>
>
> On 9/7/06, Paul Keating <pkeating at bank-banque-canada.ca> wrote:
> >
> > This is confusing due to the fact that the tape sizes are variable.
> > This doesn't fit into the paradigm most of use are used to with tape.
> >
> > if you want to use fewer tape IDs, you should probably increase the MPX
> > level, and somehow force larger amounts of data on each tape ID. (increase
> > min size of media ID)
> >
> > with only 4 drives, you can only run 4 streams at once, unless you have
> > a MPX >= 1, (max # of streams := # of drives x MPX) so I'm a little
> > confused as to how the number of streams affects the number of media IDs
> > used, unless the CDL marks a tape as "full" at the end of a job.
> >
> > The variable size media thing is confusing. I would be interested in
> > browsing the CDL docs that describe this.....
> >
> > Paul
> >
> >
> > --
> >
> > -----Original Message-----
> > *From:* veritas-bu-bounces at mailman.eng.auburn.edu [mailto:
> > veritas-bu-bounces at mailman.eng.auburn.edu] *On Behalf Of *Veritas
> > Netbackup
> > *Sent:* September 6, 2006 3:09 PM
> > *To:* Paul Keating
> > *Cc:* veritas-bu at mailman.eng.auburn.edu
> > *Subject:* Re: [Veritas-bu] Netbackup VTL tuning
> >
> > Hi Paul,
> >
> > Thanks for your concern. Its a minimum of 5 GB that a tape can contain.
> > The tape grows tilll the max vol size.
> >
> > Since the problem appears confusing, I'l narrate some details
> >
> > 1. We have say 10 TB of VTL, I use 3 TB a day, The VTL shd ideally last
> > 3 days. But say if my vault does not complete on time, I have to free some
> > medias from the ones on VTL which have already been duplicated.
> >
> > The more I free, the more the operator uses. He fires atleast 120
> > streams at once on the system during peak.
> >
> > What I have now concluded from the lists suggestion, is that increasing
> > the MPX value of the media will help in consuming less media ids & shd i set
> > a policy for limiting number of conseq streams,.
> >
> > About the total number of media id {880} I'll check and let u know.
> >
> > Regards,
> > PP BIJU KRISHNAN
> >
> > On 9/5/06, Paul Keating <pkeating at bank-banque-canada.ca> wrote:
> > >
> > >
> > >
> > >
> > > --
> > >
> > > -----Original Message-----
> > > *From:* veritas-bu-bounces at mailman.eng.auburn.edu
> > > [mailto:veritas-bu-bounces at mailman.eng.auburn.edu
> > > ] *On Behalf Of *Veritas Netbackup
> > >
> > > Basically I would like to use less media ids and hence increase tape
> > > utilization. the VTLs can grow from 5GB and above.
> > >
> > > Can you set the tape size to start at a value higher than 5GB?
> > > I still really don't understand the issue.
> > >
> > > You have 4 drives, each will use a tape, obviously......but no more
> > > than 4 tapes can be used at once, as you only have 4 drives.
> > >
> > > so if you start 10 backups, and have 10 streams per backup, then you'd
> > > have 40 jobs running to 4 tapes, and 60 jobs queued.
> > >
> > > correct?
> > >
> > > can you provide more clarification?
> > >
> > > your data has to be all backed up, if you've got 10 TB, you've got
> > > 10TB, there's no question there.
> > > If you want it backed up to fewer virtual tape IDs, then define your
> > > virtual media as starting at 100GB or larger, is that possible with the
> > > CDL?
> > > Why the 880 ID limit? is this a limitation of the CDL? Your license?
> > >
> > > your multiplex level x your number of drives defines tha max number of
> > > jobs that can run....not the number of policies you fire.
> > >
> > > f'rinstance, I fire almost all of my policies at once...a couple
> > > hundred clients, but with 3 drives x MPX=8, a maximum of 24 jobs can run
> > > at
> > > once.....when a job is finished, if another job is queued, it writes to
> > > the
> > > same tape until the tape is full.
> > > what defines the max size of your virtual tapes?? could that be a
> > > problem?
> > >
> > > Paul
> > >
> > >
> > > ====================================================================================
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