That would match what I've heard most often. While users of most other backup products are seeing an average of 20:1 on most data, that ratio relies on having full backups to compare against. TSM's progressive incremental backup of filesystems significantly reduces the commonality that you'll achieve with filesystem backups. However, you should achieve the same commonality that other backup product users see on database and application backups because you have full backups to compare against.
VERY important: You will not see de-duplication of any kind if you're only using your Data Domain box (or any other de-dupe target) as a disk pool for caching. If you're not leaving previous versions (or previous full backups of databases) on the device, it won't have ANYTHING to compare against, and you'll end up with 2:1, as some users have mentioned. (You get 2:1 because after any de-dupe stages, they also run compression against data sent to their device.) And since most de-dupe products' pricing is based on getting a 20:1 or so de-dupe ratio, you're kind of getting ripped off. (This means that after you test what de-dupe ratio you're going to get with your data, make sure you compare the price of the de-dupe target against what you would pay for just a regular disk array. If you're getting a very low de-dupe ratio, they may be very close in price.) Finally, if you're OK with just getting 2:1, you might consider Storewiz. They are a gateway in front of your storage that does in-line Limpel-Ziv compression on your data allegedly without any performance degradation. (The idea is that while compressing obviously takes some cycles, they make up those cycles by having your disk array store 50% fewer blocks.) --- W. Curtis Preston Backup Blog @ www.backupcentral.com VP Data Protection, GlassHouse Technologies -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Cory Heikel Sent: Wednesday, October 10, 2007 6:38 AM To: [email protected] Subject: Re: [ADSM-L] TSM and Data Domain We are averaging about 11/1 with data domain on a mix of data. One thing we found was the need to update a setting for tsm tape marker parameter, which almost doubled our performance. Cory Heikel Tivoli Systems Administrator Hershey Medical Center (717) 531-7972 >>> Dirk Kastens <[EMAIL PROTECTED]> 10/10/2007 2:45 AM >>> Kenneth, Bradberry, Kenneth schrieb: > I am currently looking at Data Domain as a possible VTL and > de-duplication vender. Can anyone share there experiences with Data > Domain with TSM? We just tested a DataDomain machine with TSM. The results were not as good as we expected. It shows a very good compression with database backups (Exchange backups should also work well) but not with normal user data, like homedirectories or web data. -- Regards, Dirk Kastens Universitaet Osnabrueck, Rechenzentrum (Computer Center) Albrechtstr. 28, 49069 Osnabrueck, Germany Tel.: +49-541-969-2347, FAX: -2470
