On Tuesday April 21, johannes.segitz@xxxxxxxxx wrote: > On Tue, Apr 21, 2009 at 3:19 AM, NeilBrown <neilb@xxxxxxx> wrote: > > Have you done any testing without the crypto layer to see what effect > > that has? > > > > Can I suggest: > > > > for d in /dev/sd[gjk]1 /dev/md6 /dev/mapper/data bigfile > > do > > dd if=$d of=/dev/null bs=1M count=100 > > done > > > > and report the times. > > tested it with 1gb instead of 100 mb > > sdg > 1048576000 bytes (1.0 GB) copied, 9.89311 s, 106 MB/s > sdj > 1048576000 bytes (1.0 GB) copied, 10.094 s, 104 MB/s > sdk > 1048576000 bytes (1.0 GB) copied, 8.53513 s, 123 MB/s > /dev/md6 > 1048576000 bytes (1.0 GB) copied, 11.4741 s, 91.4 MB/s > /dev/mapper/data > 1048576000 bytes (1.0 GB) copied, 34.4544 s, 30.4 MB/s > bigfile > 1048576000 bytes (1.0 GB) copied, 26.6532 s, 39.3 MB/s > > so the crypto indeed slows it down (and i'm surprised that it's that > bad because i've read > it's not a big hit on current CPUs and the X2 isn't new but not that > old) but still read speed > from md6 is worse than from one drive alone I suspect you will see that improve when you add another drive that it isn't running degraded. NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
