I have tested initially 2 lpar on the same p710 using virtual ethernet adapter and have the same result 1.5MB/s. There was no switch between,just using the hypervisor
1 lpar aix 7.1 as target.the other aix 7.1 lpar as initiator.
It seems in my config, aix target has limitation is 8MB/s and the initiator has a limitation of 1.5MB/s. That is not acceptable. I must change a parameter somewhere to have acceptable results but don't know what...
Tune network options and interface parameters for maximum iSCSI I/O throughput on the AIX system as follows:
Enable the RFC 1323 network option.
Set up the tcp_sendspace, tcp_recvspace, sb_max, and mtu_size network options and network interface options to appropriate values. The iSCSI Software Initiator's maximum transfer size is 256 KB. Assuming that the system maximums for tcp_sendspace and tcp_recvspace are set to 262144 bytes, an ifconfig command used to configure a gigabit Ethernet interface might look like the following: ifconfig en2 10.1.2.216 mtu 9000 tcp_sendspace 262144 tcp_recvspace 262144
Set the sb_max network option to at least 524288, and preferably 1048576.
Set the mtu_size to 9000.
For some iSCSI targets, the TCP Nagle algoritm must be disabled for best performance. Use the no command to set the tcp_nagle_limit parameter to 0, which will disable the Nagle algorithm.
Thanks for helping, I had already tested your recommendation but still the same.
I still think it is a limitation on AIX (a magic parameter to change?)
To prove it, I have now narrowed down this issue, I have installed RHEL 6.5 ppc64 on the p710 and set it up as iscsi initiator, the other RHEL 6.5 x86_64 physical (not a VM) as iscsi target
I have now really good iscsi transfer rate ! :
Code:
[root@localhost ~]# dd if=/dev/sdb of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 9.90109 s, 108 MB/s
[root@localhost ~]# dd if=/dev/sdb of=/dev/null
^C1633537+0 records in
1633536+0 records out
836370432 bytes (836 MB) copied, 10.6675 s, 78.4 MB/s
[root@localhost ~]#
Any idea ? any magic parameter on AIX to change that may help ?
Last edited by frenchy59; 07-22-2016 at 10:40 PM..
Reason: typo and add code tag
I think I got my answer, I was simply dd if=/dev/hdiskX ... and I should have done dd if=/dev/rhdiskX ... using the raw device instead of the block device increased the instate result significantly !
Although on linux I was using the block device, I didn't get such difference with the raw device that's why it was confusing.
Thanks for your help guys.
Last edited by Don Cragun; 08-13-2016 at 06:28 PM..
Reason: Add ICODE tags.
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08-13-2016
