On Thu, 6 Jan 2005 17:10:17 +0100, Pieter Hulshoff
On Thursday 06 January 2005 16:58, Greg Freemyer wrote:
On Thu, 6 Jan 2005 11:13:58 +0100, Pieter Hulshoff
For pure disk performance, one tuning trick I found with 9.2 is to use "noapic" on the kernel boot line. It increased my disk speed 20-30%. Done that already. My soundcard's giving me headaches if I don't use noapic.
Also, how are you measuring performance?
copying: time cp <file1> <file2>
Then the filesystem comes into play. I mostly move 640 MB files around. I find the xfs filesystem is about 30% faster than ext2. (Yes, I was shocked the first time I compared them.) That is very filesize dependent, so you need to pick the filesystem best suited for your need. Also, are you copying to/from the same physical disks? If so, I don't kow how much raid-0 is buying you. I think you said you had 4 disks, if you need speed (and I know I do), then you might be better off to setup 2 raid-0 of 2 disks each. Then copy between them. Even if you have to double copy, it will likely be faster.
hdparm: hdparm -tT /dev/hd<drive>
You can do that on a software raid? Somehow, I would not trust the result. And if you are saying your Raid-0 file copy is only going as fast as hdparm is reporting, then you are comparing apples and oranges. The copy has filesystem overhead that the hdparm does not have. Another couple tests you could use are: for raw read performance (only do this while not mounted!!!): umount raid-0 dd if=raid-0 of=/dev/null (running iostat -d 5 in another shell session). For filesystem read/write: dd if=large-file-on-raid0-filesystem of=/dev/null (running iostat -d 5 in another shell session). dd if=/dev/zero of=file-on-raid0-filesystem
Regards,
Pieter Hulshoff
I hope someone gives you the answer to your raid-0 question. The only thing I can think of is if you are mounting with the sync flag. That is pretty non-standard, but it would prevent raid-0 from bufferring and thus, no performance gain. FYI: I am going to setup a hardware raid-0 based on 3ware and do some performance testing with it. I have not done that, but it might be informative as part of the troubleshooting. Greg -- Greg Freemyer