I just got a HP DL180 G6 that has 25X 146GB 15K SAS drives, 36GB RAM, 2X 2.0GHz Xeon 1333Mhz FSB. For fun I configured them all in a single RAID 0 and installed Ubuntu on it to see how fast it could get with 25 drives on a HP Smart Array P410 Controller w/ 512MB RAM.
When I ran hdparm -tT /dev/mapper/concorde--vg-root I get
Timing cached reads: 5658MB in 1.99 seconds = 2834.13 MB/sec Timing buffered disk reads: 1192 MB in 3.00 seconds = 397.13 MB/sec
When I run the same command on my other server (HP DL360 G5 - 32GB RAM - 2X 2.66GHz 667Mhz FSB) that only has 4X 15K drives I get:
Timing cached reads: 13268 MB in 1.99 seconds = 6665.18 MB/sec Timing buffered disk reads: 712 MB in 3.00 seconds = 237.17 MB/sec
I would have expected this to run 5 times faster than the old one, not slower. The server is intended to deliver streaming media and so I need super fast access and transfer to keep up with 2 1Gb network ports I hope to max out at times along with performing it's other tasks.
I just put together a bunch of copies of a 400MB MP4 file to get 45GB to copy from one directory to another and it took 96 seconds, which just seems wrong for everything I have ever heard of the performance boost of RAID 0.
It is setup as a hardware raid, is there anything I need to do in Linux to take advantage of the extra speed that should be there? Does it matter which flavor of Linux I use? I am comfortable with CentOS and Ubuntu but could do others if needed.
Is there a different command I should use to measure performance? I tried using iotop and iostat yesterday to monitor the RAID usage and couldn't get it to report any usage while copying 2GB files over FTP, so kind of stuck trying to set a benchmark, comparing it's performance across servers, and monitoring it so I know when the hard drives are maxing out and need to be replaced with SSD.