Interesting. Differences in IBM vs. HP LTO3 drives:
I have been told that the IBM drives do "smart" compression using a bypass buffer. If a block of data is going to expand during compression, the IBM drives will stop compression and write the uncompressed block, which should make them a bit faster. Re tape to tape operations: I have observed the same behavior; tape to tape operations are inexplicably slower than you would expect when the TSM server is on WINDOWS. I have observed this with fibre drives, and SCSI drives, 3590 and LTO. I suspect it has something to do with buffer use, but since Windows provides no tools whatever to measure performance of tape devices or buses with tapes on them, I've never been able to make any other determination. I don't think it is a READ issue with the drives. Try testing using an AUDIT; that just reads the tape and doesn't write anything. I suspect you'll get faster READ times. I would be interested in seeing your results! Wanda Prather "I/O, I/O, It's all about I/O" -(me) -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Henrik Wahlstedt Sent: Thursday, December 14, 2006 10:37 AM To: [email protected] Subject: Performance with move data and LTO3 Hi, I wonder what transfer rates (move data from drive to drive) I am supposed to see with LTO3. I have two TSM servers, one 32-bit Win2k3 and one 64-bit 2.6.9-11.Elsmp, with a SL500 and FC LTO3 drives. Similar HW (HP DL585) except for one server have HP- and the other have IBM drives. Drives are on separate PCI busses. I used a dataset of 50Gb with large files, same file type on both systems. Only scratch tapes and no expiration on the datasets. No other tape activity on the systems during the tests. I tested disk->mt0->mt1->mt2->mt3->mt1->mt0->disk >From disk to tape I get a throughput of 74-76Mb/s with IBM drives, (migration). >From tape to tape, (move data), with HP drives I get a throughput of 30-46Mb/s and with IBM drives I get 39-59Mb/s. >From disk to tape, (move data), with IBM drives I get a throughput of 44Mb/s. Apperently write speed seems OK but read spead is an issue?! Or is this normal? Thanks Henrik ------------------------------------------------------------------- The information contained in this message may be CONFIDENTIAL and is intended for the addressee only. Any unauthorised use, dissemination of the information or copying of this message is prohibited. If you are not the addressee, please notify the sender immediately by return e-mail and delete this message. Thank you.
