I'll share my experiences with primary TSM diskpool on SATA drives for the list, since this subject is becoming more common lately.
Environment: TSM 5.3.4.0, AIX 5300-04-03, 1 CPU 4GB RAM LPAR on a p570 2 HBAs for disk, 1 HBA for 2 LTO3 drives Backup is roughly 650GB nightly and will more than double very soon EMC Clariion CX500, Flare code 19, default cache settings - 8kb block size, etc. I originally had only 5 7200RPM 250GB SATA drives to work with That has now changed where I'm spread across 10 drives I first started by trying out RAID5 just to see what I could get. Not much. Roughly 25MB/sec writes to a single 4+1 RAID5 array. I next switched to a single 4+1 RAID3 array. After some JFS2 tuning I maxed out at 77MB/sec writes, 123MB/sec reads (migration). I was able to go beyond my 5 SATA disks and use 5 others as well. I went to 2 4+1 RAID3 arrays with a usable capacity of about 1823GB each. I carved up one 900GB LUN on each array and assigned it to TSM. Element size on each array was the default - 128 blocks, 64K Each 900GB LUN is owned by a different SP on the CX500. I experimented by creating a striped LV across both LUNs with various stripe sizes and then used define vol diskpool xxxx formatsize=xxx to create a diskpool volume. I used topas to monitor disk performance. Performance was rather equal until 8K or 4K stripe sizes, which resulted in slightly lower performance. I settled on a 64K stripe size for the striped LV. That resulted in the same 77MB/sec writes from each array for a total of 154MB/sec. I imagine getting another 5 drives and using another array to stripe across would be even better. I'm not sure at what point the SPs/subsystem would max out, but it was showing 60% utilization on one SP while I was running at max - there are also some mirrorview volumes and other production data on the fibre drives in this same CX500 so the entire subsystem is not dedicated to TSM. The plan was to use the remaining free space on those SATA arrays for clone LUNs, but we have yet to see if that is really feasible. If anyone has any other tuning tips I'd be happy to listen. ______________________________ John Monahan Consultant Infrastructure Solutions Computech Resources, Inc. Office: 952-833-0930 ext 109 Cell: 952-221-6938 http://www.computechresources.com
