Capo,
I implement and support both large and small environments with VTLs,
and have had a lot of practice. I will weigh in on your questions, but
there are more issues involved to really get the best design for your
sitation. Contact me offline if you want to discuss further.
1. TSM catalog is growing too much. Would VTL help them to reduce
its size ? When data are copied offline (I suppose via a copy pool),
does the catalog still keeps track of them?
No, the TSM database contains all backup objects, no matter what storage
pool they are in. If a copy storage pool is made, the database keeps
track of those objects, too.
2. Physical tape generation from Virtual media is really important
in this project: customer would like to keep fresh backups on VTL and
old ones on tape. With other BU applications this would be quite easy
but, since TSM has got a peculiar way to manage files (versions), I am a
confused: do you think that defining the tape library as a copy pool is
a good idea? What level of granularity can I reach with the storage
policies and copy pools? Can I simulate the lifecycle policy of other
backup applications ? Can I tell migrate XX backup to tape after 1 month
and remove it from the VTL and stuff like that ?
You have a few choices here, depending on how much VTL disk you can
afford, and your requirements:
- If your virtual library is sized large enough, you can keep all your
Primary data on the VTL. A physical library is used for copy storage
pools for offsite storage, and backups of the TSM database.
- The VTL can be used for multiple storage pools, so some storage pools
can hold client data that never migrates to tape (the VERY important
clients) and other clients can migrate to tape so the VTL doesn't get
full.
- If your VTL can't hold all your primary data, you can set up automatic
migration. You can set up the storage pool to only migrate data after
it is a certain number of days old.
- You can also set up a storage pool so the data keeps the most recent
version of each file on the VTL, and only migrates to tape the older
version.
3. Any real life experience to share ? The candidates for this
project are Centricstor and DXi 7500 (or the new DXi 8500).
I can't claim personal knowledge of either of those products; I am most
familiar with the EMC Disk Library. Neither of those products is one of
the major VTLs, but that doesn't mean they won't work. But when
evaluating any of these VTLs, consider the possibility of an outage in
your design. In other words, if you have problems with your VTL and it
is down for awhile, what is your contingency plan? If you have a VTL
from a major vendor with good support in your town, you may never
experience an outage of more than a few hours. If you buy a low-end
product with no local support, you could be down for days when that
happens. You may be able to live with that risk, but you should discuss
it in advance. Do you need a couple TBs of disk on standby somewhere,
so you can use it for disk storage pool so you don't loose backups if
the VTL is down? Can your customers live through a long period of time
when nothing can be restored because the VTL is down? These are the
things that cause customers to buy the high-end products with good
hardware support capabilities. Consider the costs/benefits of what each
vendor offers, not just in price and performance, but in support.
Because one day your are going to need it.
Best Regards,
John D. Schneider
The Computer Coaching Community, LLC; a TSM Consulting Company
Office: (314) 635-5424 / Toll Free: (866) 796-9226
Cell: (314) 750-8721
-------- Original Message --------
Subject: [ADSM-L] TSM + VTL and physical tape library
From: Capo <tsm-forum AT BACKUPCENTRAL DOT COM>
Date: Fri, October 15, 2010 3:35 am
To: ADSM-L AT VM.MARIST DOT EDU
Hi all,
I'm involved in a TSM + VTL project but, unfortunately, I'm quite
new in TSM world: please apology me if I make trivial questions:
My customer has currently got 4 TSM instances copying to a small
disk pool and then to an IBM Tape library.
They would like to introduce a VTL in the existing environment to
improve overall performances and give TSM servers a little break.
My questions:
1. TSM catalog is growing too much. Would VTL help them to reduce
its size ? When data are copied offline (I suppose via a copy pool),
does the catalog still keeps track of them?
2. Physical tape generation from Virtual media is really important
in this project: customer would like to keep fresh backups on VTL and
old ones on tape. With other BU applications this would be quite easy
but, since TSM has got a peculiar way to manage files (versions), I am a
confused: do you think that defining the tape library as a copy pool is
a good idea? What level of granularity can I reach with the storage
policies and copy pools? Can I simulate the lifecycle policy of other
backup applications ? Can I tell migrate XX backup to tape after 1 month
and remove it from the VTL and stuff like that ?
3. Any real life experience to share ? The candidates for this
project are Centricstor and DXi 7500 (or the new DXi 8500).
Thanks for your help
Max
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