did you get any further on this ? I was about to start a new thread till I saw this, so thought I'd add to it.
I have the same problem, on pretty simple hardware. Doing dd tests to individual drives I get great speed, but doing dd to a large file, I get crap read speed. I have tried turning prefetch off but no diff. I have found though that reading small files (approx up to 3GB) is ok, but anything over 3GB just dies in the ar$e. I did 2 read tests, 1 after the other. First file was 2.9GB and it's read speed was fine, the 2nd was 3.9GB and it was very slow. From testing reads of other large files, it seems the size of the file have a big bearing on this problem happening. My home server houses 2TB of home videos (all uncompressed)...and up until now nearly all my operations have been writes and the speed has been fine...but now I need to read, and it's simply not working.. I had thought I had a dodgy SATA port on the motherboard, but I have tried swapping drives around to different ports and replaced cables all to no avail. I had been seeing some AHCI time out errors, but these have since stopped (not sure why they appeared and then why they stopped). Anyone have any ideas why reads from large files will show extremely crap read performance from a ZFS raidz, but files under 3GB are fine ??? Thanks Tim -- This message posted from opensolaris.org _______________________________________________ storage-discuss mailing list storage-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/storage-discuss
