Poor iSCSI performance with istgt.

[Peter Ankerstål]

On 11/19/2012 04:05 PM, Daniel Braniss wrote:
>>
>> On 11/19/2012 02:48 PM, Daniel Braniss wrote:
>>> try increasing the tag opening - see camcontrol(8)
>>>
>>> danny
>>>
>>>
>>>
>> I tried camcontrol tags daX -N 32 (and a few different values) but cant
>> see any change in speeds.
>>
>> (pass25:iscsi0:0:0:0): dev_openings  30
>> (pass25:iscsi0:0:0:0): dev_active    2
>> (pass25:iscsi0:0:0:0): devq_openings 30
>> (pass25:iscsi0:0:0:0): devq_queued   0
>> (pass25:iscsi0:0:0:0): held          0
>> (pass25:iscsi0:0:0:0): mintags       2
>> (pass25:iscsi0:0:0:0): maxtags       255
>
> I think there is some magic to allow istgt to do tagging, but at the moment
> can't find it, sorry.

Hm!

When increasing the tag openings to 8 (for example) I get extremley good 
reads. I saturate the network (arount 550MB/s). But writes becomes even 
more slow (around 1-2MB/s). So it seems the iscsi setup is capable of 
hadling the speeds I want but for some reason writes are f*ed up.