On Tue, Apr 20, 2010 at 02:19:13PM -0700, Tracy Reed wrote: > > How do you know this is a mis-aligned sectors issue? Is this what your > > AOE vendor is telling you ? > > No AoE vendor involved. I am using the free stuff. I think it is a > misalignment issue because during a purely write test it is doing > massive amounts of reading according to iostat.
How about actually verifying that by e.g. using wireshark and comparing the I/O patterns in the fast and slow cases? The differences in the patterns may give clues where to look further. > #dd if=/dev/zero of=/dev/etherd/e6.1 oflag=direct bs=4096 > count=3000000 > 1764883+0 records in > 1764883+0 records out > 7228960768 bytes (7.2 GB) copied, 402.852 seconds, 17.9 MB/s > > But even on my local directly attached SATA workstation disk when > doing that same dd on an otherwise idle machine I see performance > like: > > $ dd if=/dev/zero of=foo.test bs=4096 count=4000000 > C755202+0 records in > 755202+0 records out > 3093307392 bytes (3.1 GB) copied, 128.552 s, 24.1 MB/s > > which again suggests that oflag=direct isn't doing quite what I expect. oflag=direct turns off caching on the host dd is running on, i.e. the initiator. The target still caches writes of course, unless you tell it not to by passing the "-d" flag to vblade. Gabor ------------------------------------------------------------------------------ _______________________________________________ Aoetools-discuss mailing list Aoetools-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aoetools-discuss
