I'm running CentOS 5.2 targets w/ a 2.6.24 kernel. The initiator is Win2003. On the initiator side, the fs is formated NTFS w/ a 4K block size (and the NTFS block size seems to have nothing to do w/ this issue). Watching iostat on the target side, everything is being written to the underlying disk in 512 byte operations. Best I can tell, it's the Linux side that's fragmenting the I/O. I could get a lot better performance if these were coalesced into larger, variable, block sizes (i.e. what's being written from the initiator side is much larger blocks). Is there something tgtd queries on the disk to get this information? I don't see an fstat64 use of st_blksize in the source. I can put a dummy md "linear" device atop the disk and set the MD device's chunk size to 4K... then everything to the MD device (as well as to the underlying disk) is passed in 4K blocks... which performs much better (except even larger blocks would get better performance if the user is writing larger blocks... and smaller blocks do a read-modify-write that causes 3x the IO activity to perform). Where is this getting fragmented, and any idea how to fix it? Thanks, Chris -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
