Actually, it IS just a big chunk of SATA disk with sequential files, not
a "formal" VTL.
I should have explained, I was using "VTL" the concept, not "VTL" a
product!
But I"ll give you my thinking, anyway:
Advantages to using a VTL(the product):
* The VTL software does compression for you. We have to set up
our clients to do compression. If your client data isn't already
compressed, and you are MOVING existing data from tape back to a pool of
disk - it's gonna expand again. (We've been using client compression
for the last year because I was planning for this.)
* more of a "drop in" and forget it solution, less setup knowledge
required (probably not an issue for very experienced TSM admins)
Advantage of having "just a pool of disk"
* probably more flexible in terms of being able to expand at will.
We can add-replace drawers with bigger drives. We can add to our
solution with disk from a different VENDOR if we want. My past
experience is that the more generic and expandable your hardware
solution, the longer you are able to get return on the investment.
* I'm not jazzed that several of the VTL's on the market use
software that comes from a from a 3rd party (shades of Emc buys Clarion
buys Legato buys OTG etc. Just don't want to go there. Don't' want to
have to think about what happens to my support 3 years from now.)
BUT, our decision actually was determined by some VERY UNIQUE
requirements we have for purging sensitive data if we need to. We
create smaller LUNS than most people would so that we can segregate them
and replace chunks of disk physically when we need to. (Don't ask.) In
other words, we wanted more control over the internal placement of data.
I think depending on your installation, either can be an excellent
solution.
If you need something relatively small, drop in, VTL is a better way to
go (with a VENDOR YOU TRUST TO BE AROUND FOR A WHILE).
If your shop doesn't have TSM skills, or time to think about it, a VTL
is a better way to go
If you are growing very fast, understand the technology, and need
something with a lot of expandability, I would look more at building
your own solution from building blocks you can be flexible with (and a
VENDOR YOU TRUST TO BE AROUND FOR A WHILE).
My opinions and nobody else's..
Wanda.
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Leigh Reed
Sent: Wednesday, February 15, 2006 5:32 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Offsite library via fiber (Specifically VTL)
Wanda
I would be intrigued to know your thoughts on why you went specifically
with a VTL with TSM and not a more generic 'low cost' disk arrangement
with sequential files. It is a decision that I am trying to come to
terms with myself and have not yet settled in my mind which I prefer.
Apart from price, if you take into consideration ease of
management/configuration and performance, what decision making processes
did those 2 variables lead you through.
Did you go with IBM TS7510 or EMC CDL or a n other ?
I guess the last $64M question is, are you happy with the decision you
made ?
Many thanks
Leigh
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Prather, Wanda
Sent: 13 February 2006 19:31
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Offsite library via fiber
We're doing just that.
Easy to set up if your offsite location is within fibre distance.
Only we are putting the VTL (primary pool) OFFSITE and the 3584 (copy
pool) ONSITE.
Why?
1) Tapes jam. Drives break. The 3584 is very reliable, but still
mechanical. Easier to have it onsite, near us, to manage. The VTL is
essentially lights out, so it will live offsite.
2) IF we have a disaster, having the VTL offsite means we can do DR
restores without being limited by the number of tape drives we have.
Cool idea, huh? Means we only need 2 drives in our 3584. Collocation &
tape mounts are no longer an issue.
And another cool thing:
3) We're even putting a spare Windows server offsite with the VTL, and
making it a backup domain controller. TSM is already installed on it,
but inactive. If we have a disaster, all we have to do is restore the
TSM DB. We can start restoring files then to any machine we can get IP
connectivity to. Our domain is still up, we don't have to recover AD.
I can hardly wait for the tornado!
Wanda Prather
"I/O, I/O, It's all about I/O" -(me)
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
David E Ehresman
Sent: Friday, February 10, 2006 3:54 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Offsite library via fiber
We're thinking of a TSM upgrade that would include a VTL onsite library
and an IBM 3584 library for copy pool tape. We would locate the 3584 in
our offsite storage location and access it via fiber. The tapes would
remain in the 3584 since they would already be offsite.
Anyone have any experience with a setup like this?
Daivd Ehresman
University of Louisville
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