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Poor ISCSI  Performance

Posted on 2009-07-07
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Last Modified: 2013-11-14
I am getting dismal performance when copying to or from my ISCSI SAN.  

My copy speed is averaging around 20MB/s.  This seems quite slow by ISCSI standards.

Hardware is listed below:
Dell PowerEdge 2800 with 2 Intel Pro/1000 PT Server adapters dedicated to SAN.
(Windows Server 2003, SP2, 4GB RAM)
Dell PowerConnect 5424 switch.
IStor IS325 ISCSI SAN.
I am using MS ISCSI Initiator 2.08

I have taken the following steps in an attempt to improve performance:
Checked the "Enable advanced performance" option in the drive policies.
Enabled Jumbo frames on the NIC's, set to 4088.
Enabled Jumbo frames on the switch, no place to specify MTU size.
Enabled Jumbo frames on SAN LAG, set to 4088.
Flow control is set to Generate and Respond on the NIC's.
Flow control is enabled on all the switch ports.
Spanning Tree is disabled on the switch.
At the SAN, ports 1 and 3 are grouped in a LAG (Jumbo frames set to 4088)

Any help is GREATLY appreciated.


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Question by:richbrewer
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9 Comments
 
LVL 42

Expert Comment

by:paulsolov
ID: 24800027
Set port duplex and speed to full/1000 on the server if you haven't done so already.  If you're doing LAG make sure your SAN and switch are configured to match otherwise you'll have flapping on the ports since you may have source traffice come in on a different interface.

As a baseline (if this is the only LUN you have on the SAN) use a crossover cable from the server to the SAN, this will take the switch out of the equation.



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Author Comment

by:richbrewer
ID: 24802702
Thanks paulsolov,

I negleted to mention, but I do have d uplex and speed set to full and 1000.  Also, the SAN ports are grouped in a LAG as well as the switch ports that are connected to the SAN LAG.

I have two LUNs on the SAN.  Could I use two crossover cables from my Intel NICs to the SAN?
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LVL 42

Accepted Solution

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paulsolov earned 500 total points
ID: 24802726
I would do the baseline without the LACP/LAG configured, this will let us know whether it's LACP/LAG that's causing the issue.  If you're using LACP/LAG make sure you have IP Hashing set up on your vswitch though.

I would start with a single access port using crossover and go from there so we can modularize the testing process.
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Author Comment

by:richbrewer
ID: 24853573
As this is a production server, I have to operate within acceptable outages.  I currently do not have one scheduled.
0
 

Author Comment

by:richbrewer
ID: 24969345
paulsolov,

As it turns out, I am lacking the time to test the server.  I am willing to accept your answer for your efforts, but I'm not sure that is in the best interest of anyone who may be searching for an answer to a similar problem.  I am being forced to abandon the troubleshooting for the time being and will not be able to work on this problem for some time.

Recommendations?
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LVL 42

Expert Comment

by:paulsolov
ID: 24969752
see if you can configure a LUN and a spare PC/Server.  I would then setup two ports and see if you can repliate it on a different system/lun to baseline.  You can even use a windows XP workstation with MS iSCSI initiator until you have time for maintenance window to troubleshoot
0
 

Author Comment

by:richbrewer
ID: 24969787
I may not have been clear.

I meant I am not able to put any time into this problem until a future date.

I was asking for recommendations on how to handle this question.  
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LVL 42

Expert Comment

by:paulsolov
ID: 24969857
Your choice.  You can close it and when you have time open another ticket when you're ready to troubleshoot.
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LVL 42

Expert Comment

by:paulsolov
ID: 24969971
you can shoot me an email when you're ready to troubleshoot further
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