Have you tried using fewer tape drives?! Crazy as that sounds, if you can't feed the 4 drives fast enough, they are all going to shoe-shine which will kill throughput. Fewer tape drives would also reduce the seek load on the disk pool (where again, the heads are hop-scotching all around trying to satisfy 4 migration processes in addition to your write load (backups)). Just a thought. -Ken
-----Original Message----- From: ADSM: Dist Stor Manager [mailto:ads...@vm.marist.edu] On Behalf Of Dury, John C. Sent: Wednesday, February 24, 2010 8:42 AM To: ADSM-L@VM.MARIST.EDU Subject: Disk Storage pool filling faster than it is emptying. ideas? We have a 3 TB disk storage pool that until recently, has been filling up partially during backups, and then emptying as the data is migrated to tape. The storage pool is now at 84% and climbing. I have 4 LTO4 Ultrium drives that can't seem to migrate the data fast enough at all. Watching nmon, I am only getting around 30MB/s total when all four drives are in use. They are all assigned to ne HBA because of a lack of slots in the AIX server. I previously had cache turned on for the disk storage pool (it is now off), so I am wondering if the terrible performance is because the disk storage pool is extremely fragmented because cache was turned on for so long. Any ideas how to offload the data to tape faster? John
