Re: Network very very slow... was iSCSI and jumbo frames

[BERTRAND Joël <joel.bertrand%systella.fr@localhost>]

Paul Ripke a écrit :
>> legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=10 bs=10m
>> 10+0 records in
>> 10+0 records out
>> 104857600 bytes transferred in 0.537 secs (195265549 bytes/sec)
>> legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=10 bs=100m
>> 10+0 records in
>> 10+0 records out
>> 1048576000 bytes transferred in 53.396 secs (19637725 bytes/sec)
>> legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=10 bs=1000m
>> 10+0 records in
>> 10+0 records out
>> 10485760000 bytes transferred in 1026.927 secs (10210813 bytes/sec)
>> legendre#
> 
> How much RAM does this system have?

	NetBSD : 16GB
	NAS : 1GB but I think I have some 4 or 8GB DDR3L somewhere.

> I'm guessing you might be paging in
> those last two operations. Instead, try:
> 
> dd if=/dev/zero of=/opt/bacula/test.dd count=100 bs=1m

legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=100 bs=1m
100+0 records in
100+0 records out
104857600 bytes transferred in 0.313 secs (335008306 bytes/sec)

> dd if=/dev/zero of=/opt/bacula/test.dd count=1000 bs=1m

legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=1000 bs=1m
1000+0 records in
1000+0 records out
1048576000 bytes transferred in 53.680 secs (19533830 bytes/sec)

> dd if=/dev/zero of=/opt/bacula/test.dd count=10000 bs=1m
legendre# dd if=/dev/zero of=/opt/bacula/test.dd count=10000 bs=1m
10000+0 records in
10000+0 records out
10485760000 bytes transferred in 1046.321 secs (10021551 bytes/sec)

On NAS side, during last dd, I note :
- iops (on one disk) : 39/s
- latency : 3 ms
- cpu : less than 10%
- free memory : 500 MB.

	JKB