Hello, we employ Infiniband SRP storage. For basic tests I just did write/read with dd to the raw block device like /dev/sda. I tell dd to use 1M sized blocks, but I see very small few KB sized requests only. To make this tests of real value I would need to read and write with large 1MB sized requests. More important I'm not sure whether this points to some misconfiguration. Example: Read 1M sized blocks from /dev/sdh - iostat shows 8*512byte average request size, which is very small, I would expect 1M sized requests: # dd if=/dev/sdh of=/dev/null bs=1M & # iostat -xk /dev/sdh 2 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sdh 0.00 0.00 8253.23 0.00 33012.94 0.00 8.00 0.90 0.11 0.11 89.95 Performance counters on the srp target show the same small request size. Is this expected behaviour if I write or read from/to a srp block device file? Does anything limit the request size if I access the storage via the block device file like /dev/sdh? Using a mounted filesystem on top of the block devices I get perfectly 1M sized i/o requests, hence I think that the storage (DDN S2A9900) is o.k.. Kind regards, Heiner Billich -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
