Since you have caching turned off now and have emptied the diskpool (?) fragmentation should not be an issue.
What is the performance when using only a single LTO4 drive, 1/4 of 30mb/s or 30mb/s? Check the read performance of the disk with dd or something similar. What speed do other tape operations get, ie reclamation, backup stg, dbbackup? Have you checked errpt for scsi/tape/disk errors? What kind of HBA is it, 1/2/4/8Gbps? NPIV or native? How about moving data from tape up to disk, test if that will be limited to 30mb/s as well. On 24/02, Dury, John C. wrote: > 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
