Note: I'm fairly new to using Linux so it is more than likely that I just simply have missed some configuration I need to setup correctly but here is my problem.

I am building a small RAID based device using 8x1TB SATA disks, a LSI-MegaRAID 9260-8i PCIe adapter and T7400 Core2 2.16GHz based mboard with 4GB Ram running Ubuntu 9.04. I have configured the disks as RAID-0, for testing purposes, and formatted a 1.8TB partition with ext2. I have written a simple app to just write/read 8MB files but do not get the performance levels expected.

When using file descriptors I get approx only 200MBs write and 220MBs read performance.
When using streams I get approx 490MBs write and 217MBs read performance.
I have also run bonnie++ and get approx 670MBs sequential block out and only 255MBs sequential read performance.

As a benchmark I have run the same configuration under windows (with NTFS) and achieved over 670MBs for both read and write, which is near what I would expect this combination of drives to be achieving (each drive is individually capable of near 120MBs on outer cylinders). I'm totally confused why I should be getting such differences and would really appreciate any advice as to the best way to achieve the fastest possible data throughput.

Have you updated to the most recent kernel and made sure the raid driver configuration in the kernel is optimal? You didn't specify if you were using a software raid or hardware raid... which are you currently using?

Hi,
I'm using a hardware raid, I think. I haven't set any kernel configuration really, not sure how but would appreciate any info on this if this is what I need to do. The raid array was built under windows and I simply reformatted the array (1.8TB) from NTFS to ext2 using gparted. I have assumed the driver is part of the Kernel build (I have Kernel 2.6.28-18-generic), dmesg indicates that I have "scsi4:LSI SAS based MegaRAID driver".

The MegaRaid controller is a PCIe x8 lane card with two 4 port connectors. There doesn't seem to be a driver for my distro for this card but as it appears to work I assumed the driver was part of the Kernel. Is this assumption correct and if so would it be a basic driver and possibly not be using DMA etc?

Try ext4 maybe instead.

http://www.delltechcenter.com/page/A...t4+Performance

Also there may be some other issue I can't remember exactly. It is how the block starts. Some issue like data blocks are not started correctly and then every other write read is a two step process instead of a single block issue. Dunno where I saw that.