[OpenIndiana-discuss] ISCSI SSD Performance

[Jim Klimov]

On 2013-02-17 00:52, Grant Albitz wrote:
> Yes jim I actually used something similar to enable the 9000 mtu that's why I want familiar with the config file method.
>
> dladm set-linkprop -p mtu=9000 InterfaceName
>
>
> Flowcontrol is currently off on the zfs host but enabled by default on esxi, I am going to try enabling flow control first and if that doesn't improve anything I will disable it on both ends.


I'd also google for a way to verify that MTU=9000 frames are actually
used by both sides and that packets are not fragmented into smaller
frames and reconstructed with more overhead that would be needed if
they originally were smaller.

I don't think I've tested if dladm can enforce larger mtu's when the
NIC driver config file doesn't have it; I do know that "ifconfig mtu"
settings did fail unless I fixed up the e1000.conf (in my case) and
rebooted.

Also, since you use point-to-point cable connections, you might use
largest MTUs - like 16k, if supported by NICs on both sides.

Just in case, to also validate (perhaps replace) the cable which
connects the machines. It may be possible that some strands have
worse connectivity than others, causing jitter and retries in only
one direction. "netstat -s" might help to diagnose that...

Good luck,
//Jim