I am seeing what seems to be a notable limit on read performance of an ext3 filesystem. If anyone could offer some insight it would be helpful. Background: 12 x 500G SATA disks in a Hardware RAID enclosure connected via 2Gb/s FC to a 4 x 2.6 Ghz system with 4GB ram running RHEL4.5. Initially the enclosure was configured RAID5 10+1 parity, although I've also tried RAID 50 and currently RAID 0. I've varied chunk sizes from 64-256K. Problem: No matter what I do I cannot get the ext3 read performance above ~90MB/s. Under virtually every configuration listed above the write performance is greater than the read performance. I've run a large number of Bonnie++ and IOzone tests, but for the sake of simplicity in this email I'll just refer to simple dd's with /dev/zero. Details: Under the current RAID0 setup I see the following when dd'ing. DD 4G from /dev/zero to /dev/sdd disk (no filesystem) & sync 28 seconds DD 4G from /dev/sdd to /dev/null 32 seconds DD 4G to ext3 on /dev/sdd & sync 32 seconds DD 4G from ext3 file to /dev/null 48 seconds. I've been watching the port usage on the FC switch and it verifies what I am seeing, Writes max out near 2Gb/s but reads hit some artificial limit around 90 MB/s and never ever exceed it with the filesystem, regardless of they underlying RAID configuration. Without a filesystem the reads are atleast 50% faster, and it can be seen on the FC switch graphs as well. Any help or thoughts would be appreciated. Thanks, ~Glen _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
