Post your performance results

yoh-dah wrote:
Processing TCP packets is a huge part of the overhead as well as copying the packets in and out of network file protocol, local file system, and RAID layers.

Can someone test this out for me? The NV+ supports an FTP server. Let's see what FTP can do (both get and put). If the problem is NFS overhead, then FTP shouldn't have the same problem. FTP has overhead too, but it's small compared to NFS.

Also, you can eliminate the local file system overhead by copying to /dev/null:

dd if=/mnt/file.bin of=/dev/null bs=<rsize> count=<large>

Where *large* means something that will exceed the cache. I'm assuming the NV+ is mounted on /mnt. To do a write test, use /dev/zero. Of course, this is all done under Linux.

yoh-dah wrote:
Also, make sure when you're comparing write performance to use RAID 5, as the parity generation will add another level of overhead.

Ugh, shouldn't parity generation be done by hardware? NV+ is a hardware RAID system, isn't it?

It also depends on what you want to test. If you want to see how fast the controller can access the drives, you should use RAID0. RAID0 is your theoretical max performance. This will tell you how much overhead you have in RAID5 by comparing the results of the two tests. Using RAID0 will also tell you how much of the physical SATA disk bandwidth you're using.

To eliminate the network throughput as a potential bottleneck, use one SATA drive with RAID0, and ftp a large file into the system. This should theorectically flood the bandwidth of that single disk drive.

My goal is to determine where the bottleneck is. Doing the above tests should be able to tell us...

--jc