LTO2 writes to tape at maximum of 40MB/sec. If the data compresses 3.5:1 then your server will need to feed the tape drive at 140MB/sec to keep up with the write speed. If the data compresses 1:1 then you only need to send data at 40MB/sec. This kind of thing used to drive me nuts until I figured out it takes about 1 hour to fill one of my tapes, regardless of the amount of data written. If it takes longer then there is a problem. In your case 85 minutes is the minimum, probably a little under 2 hours is a realistic time.
Andy Huebner "You have to think 4th dimensionally." Emmitt L. Brown -----Original Message----- From: ADSM: Dist Stor Manager [mailto:ads...@vm.marist.edu] On Behalf Of David Longo Sent: Tuesday, April 27, 2010 1:44 PM To: ADSM-L@VM.MARIST.EDU Subject: [ADSM-L] Backing up Light Speed compressed files I have never been concerned with compressed files, never used compression on TSM - except on my LTO tapes. Now, we have a new situation. We have had a client with SQL DB and the DBA's do the dumps to disk and I pick up. (Can't use TDP SQL, long story.) The dumps were lately (6) 200 GB files, total 1.2 TB and growing daily. Took about 11 hours to backup directly to LTO2 tapes. DBA's just implemented using Quest's Light Speed using their Level 4 compression - whatever that is. The dumps are now (4) 62 GB files, so about a 5 to 1 compression. The TSM backup took much less time, but not as much less as expected. When the offsite copy was made, LTO2 to LTO2, I found out why. For a certain file size, it takes twice as long to back it up for a compressed file as an uncompressed file. For more info, on the LTO2 tapes, before we would get just over 700 GB on them, now just over 200 GB. (Using q vol stats). I kinew it would be less obviously. Anybody know why takes twice as long? Is there a way to speed it up? Thanks, David Longo ##################################### This message is for the named person's use only. It may contain private, proprietary, or legally privileged information. No privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it, and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. Health First reserves the right to monitor all e-mail communications through its networks. Any views or opinions expressed in this message are solely those of the individual sender, except (1) where the message states such views or opinions are on behalf of a particular entity; and (2) the sender is authorized by the entity to give such views or opinions. ##################################### This e-mail (including any attachments) is confidential and may be legally privileged. If you are not an intended recipient or an authorized representative of an intended recipient, you are prohibited from using, copying or distributing the information in this e-mail or its attachments. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete all copies of this message and any attachments. Thank you.