On 2011-05-31 20:22, Troels Arvin wrote: > Hello, > > Running fio 1.55 on RHEL 6.1 x86_64 with a multipath FC storage backend on an EXT4 file system. > > Some minutes after starting fio, I see the following in syslog: > kernel: EXT4-fs (dm-28): Unaligned AIO/DIO on inode 4063238 by fio; performance will be poor. > > Should I be worried? Is there something wrong with my storage layout? > Or am I using fio in strange way? > > My job file: > > [changed-from-iometer-file-access-server] > bssplit=512/10:1k/5:2k/5:4k/60:8k/2:16k/4:32k/4:64k/10 > rw=randrw > rwmixread=70 > direct=1 > size=10g > ioengine=libaio > iodepth=256 > write_bw_log > write_lat_log > numjobs=6 Do you have the RHEL6.1 kernel sources handy? That message is not in the upstream kernel. Unaligned could be memory, or it could be offset/size. In general O_DIRECT does not work for unaligned IO. Perhaps it's referring to writes that aren't stripe aligned, but that seems fairly expected and something dm should handle. So to render an opinion on this, I'd need to see a copy of the file that prints that message :-) -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
