Environment Server: TSM 4.2.1.7, AIX 4.3.3, two fiber gigabit ethernet cards, each accessing disk and tape (I know, this is bad, but it shouldn't impact this situation) Client: W2K, 4 processors (around 900mhz, I think), just over 3GB of physical memory, TSM B/A client 4.2.1.32, TSPSQL 2.2, Storage agent 4.2.1.7, three fiber gigabit ethernet cards (qLogic), one for disk, two for tape access. SAN: Shark ESS Node setup has 4 mountpoints allowed. Fiber Network: dual Brocade 2109 fiber switches. Library IBM 3584 with five LTO Ultrium fiber connected drives (three connected to one switch, two to the other switch). Utility used to measure speed during backups: qLogic Sanblade Manager.
Backing up a 33GB SQL database located on the Shark to one tape, I can get about 28-30 MB/second. Backing up the same database striped to two tapes, I would get about 31 MB/second. I had the DB admin spread the three files in the database over three of the four different available drive letters (actually on 2 different packs on the ESS Shark). That made my two-stripe backup in the 36-37MB/second range (single stripe backups are still in the 28-30MB/second range). I am looking to find a way to get somewhere near the 50-60MB/s range for a backup. It doesn't make sense to stripe a backup when you are only getting a 20% increase in throughput (and this works out to less than a 20% decrease in time for the backup because of the storage agent mounting tapes, locating last files, etc, one tape at a time). I am doing testing in preparation for a 500GB database. I did some tests with very large files on each of the four drive letters, simultaneously copying the large files to >nul (using four different command line prompts), to get a benchmark of data throughput on the disk fiber card. The max sustained throughput (based on the qLogic monitor) was ~66MB/second. Most of the time, the rate hovered in the 45-55 MB/second range. CPU utilization on the client node during a 2-stripe backup is around 85-95%, and during a single-stripe backup, it is around 35-45% (on all four processors). Can anyone suggest some things to check that might impact this? On another note, the backups are not completing as of my last two-stripe test. I am working with Tivoli support regarding this problem. Backups with a single stripe are working.
