UCS iSCSI SAN Configuration

Answered Question
Sep 21st, 2010
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All,


I can't seem to find any good documentation on connecting a UCS system to iSCSI SAN storage.  We run a Equallogic iSCSI SAN and I need to connect our UCS system to it.  I can find plenty of documentation on Fibre Channel but obviously that doesn't help me.  Does anyone know if any iSCSI configuration documentation that they can point me to?  I just plan on using it for storage and will NOT be trying to boot from SAN.


Thanks,


Ken

Correct Answer by Robert Burns about 6 years 10 months ago

Ken,


There's no "formal" guide for iSCSI access, but it's pretty straight forward.  It's just like setting up ethernet access to anything else. The only consideration you'd want to make is to your MTU size.  Most people will configure Jumbo MTU/Frames on their iSCSI VLAN.

This requires the following to accomplish.


1.  Creating a UCS QoS System Class with an MTU of 9000 & apply to the iSCSI vNIC(s) by Service Profile -> vNIC ->

2. Enable Jumbo Frames (MTU 9000) on all switches between Initiator (UCS) and iSCSI Target (Equalloqic).

3. Enable Jumbo Frames on OS Adapter (Vmkernel port for ESX, Network Adapter Advanced Properties on Windows)


As you can see the only UCS-specific task is the QoS policy which allows an MTU size of 9000 Bytes - assuming you're going to use jumbo frames in your environment - highly recommneded especially with 10G.


Robert

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Correct Answer
Robert Burns Tue, 09/21/2010 - 16:15
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  • Cisco Employee,

Ken,


There's no "formal" guide for iSCSI access, but it's pretty straight forward.  It's just like setting up ethernet access to anything else. The only consideration you'd want to make is to your MTU size.  Most people will configure Jumbo MTU/Frames on their iSCSI VLAN.

This requires the following to accomplish.


1.  Creating a UCS QoS System Class with an MTU of 9000 & apply to the iSCSI vNIC(s) by Service Profile -> vNIC ->

2. Enable Jumbo Frames (MTU 9000) on all switches between Initiator (UCS) and iSCSI Target (Equalloqic).

3. Enable Jumbo Frames on OS Adapter (Vmkernel port for ESX, Network Adapter Advanced Properties on Windows)


As you can see the only UCS-specific task is the QoS policy which allows an MTU size of 9000 Bytes - assuming you're going to use jumbo frames in your environment - highly recommneded especially with 10G.


Robert

DAVE GENTON Tue, 07/08/2014 - 09:16
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MUST we apply a qos system class since it can be set on the vNIC as well ??   Once I use a QoS system class then that means the CoS markings are also changing.  I fear traffic leaving with say CoS 4 and jumbo mtu leaves the system properly but returns on a path where qos is written that UCS wrongly classifies the traffic as default where the mtu is only 1500 mtu.   This is a valid issue is it not ??  I have customer with dell SAN where they used dedicated switches for iSCSI, no QoS, no markings and default queuing.  Now adding a UCS to replace their old servers I need jumbo mtu but no CoS markings to ensure to/from marking remains the same.  Make sense ?

 

 

Dave

andiputranto Tue, 05/10/2016 - 14:50
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Should we consider extra bytes header and set QoS System Class 9216 (instead of 9000) ?


Robert Burns Tue, 05/10/2016 - 15:55
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  • Cisco Employee,

Just max it out.  Certain configurations will have a max of 9000, others might extend to 9216.  Just depends if they include the headers.


Robert

andiputranto Thu, 05/19/2016 - 16:21
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Some OS support only 9000 mtu. Is FI inject the extra header (216) before sending it northbound ?  What extra header that might be ?


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