On 10/14/2014 02:15 PM, Joakim Ziegler wrote:
I have a rather large box (2x8-core Xeon, 96GB RAM) where I have a couple of disk arrays connected on an Areca controller. I just added a new external array, 8 3TB drives in RAID5, and the testing I'm doing right now is on this array, but this seems to be a problem on this machine in general, on all file systems (even, possibly, NFS, but I'm not sure about that one yet).
The first thing I would check is that you have a BBU installed on the areca controller and that it is functioning properly (check the cli, I don't know the exact commands off the top of my head), also make sure that write caching is enabled on the controller (after you've checked the BBU, of course). Without a working BBU in place hardware RAID controllers, such as areca, disable write caching (by default) and this will have a significant impact on write speeds.
Note that newer controllers use a type of flash memory instead of a BBU.
Peter