On Mar 22, 2007 20:44 -0700, brian stone wrote: > Machine A connects to machine B on a gigabit lan. Machine A sends > 1024 1MB chucks of data; 1 GB in total. Machine B, the server, reads > in the MB and writes it to a file. > > NOTE: server and client are little test programs written in C. > > Machine B (Server) hardware: > - Single (no raid) Seagate Cheetah 70G Ultra320 15K > - Quad Opteron 870 > - 16G DDR400 > - Backplane: LSI Logic / Symbios Logic 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 8) > > Sync methods include: > 1. mount with sync option > - tried sync,dirsync which added no additional overhead > 2. use O_SYNC open() flag > 3. use fdatasync() just before closing the file > - fsync() and fdatasync() produced the same results > > > EXT2 tests > ========================================== > No sync 12.3 seconds (83 MB/Sec) > mount=sync 44.3 seconds (23 MB/Sec) > O_SYNC 31.7 seconds (32 MB/Sec) > fdatasync() 31.3 seconds (32 MB/Sec) > > > EXT3 tests > =========================================== > No sync data=writeback 14.5 seconds (70 MB/Sec) > No sync data=ordered 17 seconds (60 MB/Sec) > No sync data=journal 65 seconds (15 MB/Sec) > data=ordered O_SYNC 49 seconds (20 MB/Sec) > data=ordered,sync 52 seconds (19 MB/Sec) > data=ordered fdatasync() 45.5 seconds (22 MB/Sec) > data=journal O_SYNC 72.5 seconds (14 MB/Sec) > data=journal,sync 81 seconds (12 MB/Sec) > data=journal fdatasync() 60.5 seconds (17 MB/Sec) If you are doing a large number of 1MB writes then I agree that data=journal is probably not the way to go because it means you can get at most 1/2 of the bandwidth of the disk (unless you create the journal on a separate disk). data=journal is good for small writes and lots of transactions, like mail servers that need lots of sync operations. For large writes, I'd suggest you put the journal on a separate device, and make it 1 or 2 GB (your server has plenty of RAM, so that isn't a problem). Are you using EAs, like selinux or similar? If yes, then you should also format your filesystem with large inodes (-I 256). You may also want to try out ext4dev with the mballoc and delalloc patches from Alex Tomas, as this code has been optimized for doing large power-of-two allocations in the filesystem. They've been posted to the ext4-devel lists a couple of times. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
