Contention problem
Hi,
We've got an A1000 7 disks RAID 5 plus 1 hot spare configuration with 1 controller using Volume Manager with 16 Kb stripe size and we've observed that the transference ratio does not overcome 14 MB. 鼵ould it be a reasonable limitation on the controller?
It is hosting an Oracle dB and we've discarded significant fragmentation in the tablespaces. Knowing that RAID 5 decrease performance on writing operations we've reorganized the tablespaces to minimize writing access in this array.
Thanx in advance,
[545 byte] By [
fjfpresa] at [2007-11-25 23:12:04]
# 1
Sounds like it could be RAID 5 causing some of the performance issues. I've encounter performance issues when the Oracle tablespace was residing on the same file system as the Oracle DB's. Once the tablespace was moved to its disks, a performance increase was noticed. If you are using 16k stripe sizes, make sure Oracle is set the same. However, I don't recall what the limitation is on the Oracle write sizes (maybe 8k).
# 3
Our interleaving configuration is (following the recommendations from Oracle):
Disks Stripe Size = DB_BLOCK_SIZE x
DB_FILE_MULTIBLOCK_READ_COUNT
Curiously performing some 'dd' tests tx rate did not pass 14 MB meanwhile with 2 concurrent 'dd' tasks it almost reached 30 MB !! (a much more reasonable hardware configuration limit).
