P800 Write Degradation

[jsu]

I have a P800 controller in a DL380 G5 server running W2.3K Svr Std Ed. Two of the internal SAS drives are RAID1+0 for the O/S, and the other 6 are configured RAID0, 8K stripe, 64k cluster, no compression, for temporary storage.

We run a lot of large files (2-20Gb mixed) through the temporary storage. Over time, we've noticed that the write perf has dropped off significantly... 150-180Mb/sec to 20Mb/sec.

The obvious conclusion is that it's a fragmentation problem, but because of the nature of the storage, temporary, files just don't persist. In fact, at times there are zero temporary files on the volume, nothing to defrag, and write performance is still 20Mb/sec.

- Reformatting the volume restores write performance back to normal 150+Mb/sec
- Rebooting does not address the problem

Any suggestions on what might be contributing to the write performance degradation?

Thx.