On Wed, Nov 19, 2008 at 1:12 PM, Per Jessen
Greg Freemyer wrote:
If you want to test it on a single drive, at least use dd to do your benchmarking.
These are my numbers for a 20G file on RAID1 over two SATA drives:
dd if=/tmp/file1 of=/tmp/file2 bs=512 dd if=/tmp/file1 of=/tmp/file2 bs=4k
I didn't bother with those two.
dd if=/tmp/file1 of=/tmp/file2 bs=1M
27m28s 13Mb/sec
Since 1MB was faster than 1GB for some reason, I would try the 4k one just out of curiosity, but you're likely right it is far slower. 13 MB/sec is below my guess, but not as bad as it sounds at first. Since you are reading and writing, it is really 26 MB/sec and that includes your wasted overhead of seeking around doing various stuff. I do a lot of dd if=/dev/sdX of=/file type of stuff where it is 2 separate disks involved. (No raid). 30-40 MB/sec is about typical. (60,000 to 80,000 sectors / second as shown via "iostat -d 5" I still think that is slow. I can get about twice that under Windows on the exact same (64-bit) hardware. I have not yet tried to figure it out why suse linux is slower. FYI: Raid 1 is going to be pretty close to the same speed for this as a single drive. The reads get to take advantage of having two drives to pull from, but the writes still have to go to both. So each drive is doing 3/4 of the work it would do if it was standalone. If you want better performance you need to move to raid 10, and the more spindles (drives) the better. Greg -- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org