Hello All, We've been struggling with somewhat anemic backup performance from our dedup storage pools to LTO4 tape over the past year or so. Data is ingested from clients and lands directly into our dedup pool, but doesn't get deduplicated until the offsite operation is complete. (deduprequiresbackup=yes) Our dedup pool is comprised of 50GB volumes, residing on a V7000 pool of NL-SAS drives. The drives don't appear taxed (utilization is consistently in the 30-40% range) but average throughput from the storage pool to tape is only 100-100 MB/s. This is starting to present challenges for meeting the offsite window and I am stumped as to how I might improve performance.
The TSM server is running on AIX and has four 8Gb paths to the storage, running sddpcm. Mountpoints containing the data are mounted rbrw and are JFS+ volumes. Our tape drives are running off of two dedicated 4Gb HBAs and our backup DB throughput is excellent, averaging 350-400 MB/s. For those of you that are running TSM dedup, how are you managing your offsiting process? Are you using a random devclass pool as a 'landing zone' for backup/offsite operations before migration to the dedup stg? Are there tuning parameters that you have tweaked that have shown improvement in FILE devclass stg pools to LTO devices? Any and all tips would be appreciated. I've been through the parameters listed in the perf guide and have allocated large memory pages to the TSM server but I haven't seen much, if any, improvement. Thanks! Matthew McGeary Technical Specialist PotashCorp - Saskatoon 306.933.8921
