I'm trying to figure out your question here:
Are you comparing a primary sequential pool located on a VTL, compared to a
primary disk pool? In that case, it's like comparing an apple to a pear. Using
diskpools for long-time storage is not something I'd suggest since your
diskpools will get fragemented. Also, sequential write speed is usually faster
on a sequential pool than a random disk pool.
If you're comparing a sequential pool located on a VTL, compared to a FILE
device sequential pool? In that case, you will have reclamation on both pools.
The difference however (and I can only speak for our SEPATON VTL), in case of
the SEPATON, there is never any datamovement during reclaim since it's
application aware. In case of the FILE device pool, you will have reclamation,
and you will have unnecessary data movement across the same disks when doing
reclamation.
As for performance, our 2 port SEPATON VTL easily hits 700-800MB/s with 2x4GB
ports, and it's a small one. It's upgradable to a total speed of 43.2TB/hour
(however, you will need a server, network and SAN HBA's that can actually
achieve that amount of throughput).
As for deduplication, no, a VTL cant do client-side deduplication. However, the
achieved de-dup ratio is alot higher than you will see on a TSM-based client-
or server-based dedup. And unless your network is congested, there is really no
point in doing client-side dedup, since the dedup load isnt placed on the TSM
server, but on the VTL hardware (which is one of the reasons except for a
congested network where you'd want to use client-side de-dup). I've seen other
VTL's where you need a separate VTL todo dedup. That isnt the case with our VTL
though, it's all done within the same box.
On a 2nd note, when using a FILE device pool or a diskpool, you're also missing
out on the hardware compression offered by a standard tape library or VTL. You
can probably use client-side compression, but from experience, it's never as
good as hardware compression, and puts an unnecessary load on your
backupclients (which wasnt a problem 10 years ago when working hours was during
days, today however, alot of systems are online serving customers all around
the clock).
My 5 cents worth.
Best Regards
Daniel Sparrman
Daniel Sparrman
Exist i Stockholm AB
Växel: 08-754 98 00
Fax: 08-754 97 30
daniel.sparrman AT exist DOT se
http://www.existgruppen.se
Posthusgatan 1 761 30 NORRTÄLJE
-----"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> skrev: -----
Till: ADSM-L AT VM.MARIST DOT EDU
Från: Tim Brown <tbrown AT CENHUD DOT COM>
Sänt av: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
Datum: 09/26/2011 22:05
Ärende: [ADSM-L] vtl versus file systems for pirmary pool
What advantage does VTL emulation on a disk primary storage pool have
as compared to disk storage pool that is non vtl ?
It appears to me that a non vtl system would not require the daily reclamation
process
and also allow for more client backups to occur simultaneously.
Thanks,
Tim Brown
Systems Specialist - Project Leader
Central Hudson Gas & Electric
284 South Ave
Poughkeepsie, NY 12601
Email: tbrown AT cenhud DOT com <<mailto:tbrown AT cenhud DOT com>>
Phone: 845-486-5643
Fax: 845-486-5921
Cell: 845-235-4255
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