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.sparr...@exist.se http://www.existgruppen.se Posthusgatan 1 761 30 NORRTÄLJE -----"ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> skrev: ----- Till: ADSM-L@VM.MARIST.EDU Från: Tim Brown <tbr...@cenhud.com> Sänt av: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.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: tbr...@cenhud.com <<mailto:tbr...@cenhud.com>> Phone: 845-486-5643 Fax: 845-486-5921 Cell: 845-235-4255 This message contains confidential information and is only for the intended recipient. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, please notify the sender immediately by replying to this note and deleting all copies and attachments.
