Hi, I manage a HP ProLiant DL380 G4 server connected to a MSA20 array trough an internal Smart Array 6400 controller.
Since some time, I have a problem with write speeds, which have gone terribly down.
When doing simple tests like "dd if=/dev/zero of=./testfile" I noticed that writing starts fast, but starts crawling as soon as the amount of data written reaches 800-900 MB, and then I get terrible transfer speeds between 5 and 20 MB/s.
The write cache batteries were old and needed replacement, so they have been replaced now - all four of them, two in the server and two in the array. But the problem remains.
I used ACU CLI and discovered that the cache on the 6400 controller is not enabled. Maybe it needs to be enabled again, after replacing batteries?
Anyway, I cannot find a way to enable it: the command returns an error telling that this operation is not possible with this configuration.
Instead I successfully enabled the cache on the MSA20, but it wasn't enough to fix the problem.
How can I enable the cache in the 6400? What am I missing?
The cache module should be present and correctly inserted, because all other status outputs are fine.
Any clues?
Thanks.
Marco