While doing research into poor write performance with Oracle I discovered that the server was using the LSI SAS1068E. We had a RAID1 setup with 300GB 10K RPM SAS drives. Google provided some possible insight into why we the write performance was so bad(1 2). The main problem with this card is that there is no battery backed write cache. This means that the write-cache is disabled by default. I was able to turn on the write cache using the LSI utility.
This change however did not seem to any difference on performance. At this point I came to the conclusion that the card itself is the blame. I believe that this is an inexpensive RAID card that is good for general use of RAID0 and Raid1, however for anything were write throughput is important, it might be better the spring for a something a little bit more expensive.
When it was all said and done we ended up replacing all the these LSI cards with Dell Perc 6i cards. These cards did come battery backed…which allowed us to then enable the write cache, needless to say the performance improved significantly.
