How to verify link-level flow control is working on EqualLogic?

Thanks Don.  Is it a correct statement that if the EQL array says "DCB: off" as a result of the command "member select XXXX eth select X show", it means that traditional 802.3x flow control messages will be correctly responded to by the EQL?  Second, on the switch side, the switch port physically connected to the EQL should at a minimum say "flowcontrol tx on", correct?  If it says "flowcontrol rx on tx on", that would be fine, too, I presume, but if it says "flowcontrol rx on tx off", that would be the opposite of what we would want, correct?

Re:1  Yes.  With DCB off,  pause frames will be honored by the array.  There's no setting to enable or disable it.

Re: 2.  Correct.   If the switch can't send flowcontrol it will show as off.  

However, if you have a good switch for iSCSI,  it's very rare for a switch to send a pause frame.  Pause frames are not end-to-end,  only point to point.   Typically it is the host that needs it on reads.   The array/switch on sustained READS can usually overwhelm a host.   It then sends a pause frame to the switch port its connected to.   Then only that port or port(s) are affected.   When you send a pause frame that entire port is shutdown, not just the sessions for that host.  So if you pause an array port, means multiple servers are affected.  

Regards,

Thanks Don, that really helps.  So in the case of a VMware host, it would be fairly likely for the VMware host to SEND a pause frame to the switch, which means the switch port connected to the VMware host would need "receive" flowcontrol enabled (flowcontrol rx on), correct?  Likewise, if it is rare for the switch to send a pause frame to the VMware host, then it would be OK if the switch port has "transmit" flowcontrol disabled (flowcontrol tx off), correct?

Conversely, since the EQL will never SEND a pause frame, the switch port connected to the EQL could have "flowcontrol rx off" and "flowcontrol tx on", correct?  In other words the flow control settings for the VMware host port and the EQL port would essentially be opposite settings?

That's correct.  However, don't be surprised if EQL reports TX and RX as ON.   It responds that it does, even though it will never actually send a PAUSE frame.

Hi, I have the following configuration, and read through this post wondering if I could replicate, However, I can't!?

On My Force10 S50n:

interface GigabitEthernet 0/23

description EQL iSCSI Port

no ip address

mtu 9216

switchport

flowcontrol rx on tx on

spanning-tree rstp edge-port

no shutdown

On the Equallogic Sumo

(member_Sumo2-96 eth_1)> lldp show

____________________________ Eth LLDP Information _____________________________

Name: eth1                             LLDP-State: active

System-Name: force10S50n                HardwareAddress: 00:01:**:**:16:**

System-Description: Dell Force10 Real  Chassis-Id: 00:01:**:D6:16:**

 Time Operating System Software. Dell Port-Id: GigabitEthernet 0/23

  Force10 Operating System Version:   Port-Description: EQL iSCSI Port

 1.0. Dell Force10 Application

 Software Version: 8.4.2.7. Copyright

  (c) 1999-2012 Dell Inc. All Rights

 Reserved.Build Time: Thu Sep 27

 14:03:07 PDT 2012

I'm getting many messages like this on all my vHosts:

Device naa.6090a05840a81742cc2985a411124123412 performance has

deteriorated. I/O latency increased from average value of 3451

microseconds to 69409 microseconds.

warning

1/13/2015 11:16:26 AM

*******@****.com

Device naa.6090a05840a81742cc2985a411124123412 performance has

improved. I/O latency reduced from 69409 microseconds to 13608

microseconds.

info

1/13/2015 11:16:31 AM

*******@****.com