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03-23-2011 02:04 PM
Virtual Connect Manager, SAN fabrics and dynamic load balancing question
Nick had a SAN fabric login distribution/re-distribution question:
I’m a bit confused here, when I looked at the SAN fabric on site, it showed as set to manual? Also, in the “Fibre Channel Settings” – “Misc tab” it says “Automatic login redistribution is an advanced feature that may be enabled for a virtual connect fabric. In addition to initially enabling the feature on a per fabric basis, the administrator may configure the link stability interval period”. This would seem to hint that we can still enable automatic load balancing for logins, but I cannot find where to enable it in the interface.
As I understand it Manual load balancing requires the customer to go into the Virtual Connect Manager, and manually instigate a login re-distribution, whereas automatic redistributed logins on a defined time period. However, I’m open to being told my understanding is wrong
Mark looked to clarify the issue
In the VC 3.x GUI if you create a Fabric with a port on any other VC-FC module (VC-FC 8Gb/20, VC-FC 4Gb, etc,) you will NOT get the option to show “Advanced Settings”. Because it only supports “Manual” Re-Distribution.
And to put it in simpler terms:
The confusion is “Login Distribution” vs. “Login Re-Distribution”.
Here is below summarized.
VC 2.x Firmware
· Login Distribution is configurable for “Static” or “Automatic” for VC-FC 4Gb and VC-FC 8Gb/20 Port
· Login Distribution is “Automatic” for VC-FC 8Gb/24 Port
VC 3.x Firmware
· Login Distribution is “Automatic” for all modules including the FlexFabric
· Login Re-Distribution is “Manual” for VC-FC 4Gb, VC-FC 8Gb/20 Port and VC-FC 8Gb/24 Port
· Login Re-Distribution is configurable for “Manual” or “Automatic” for FlexFabric. Default is Manual.
Comments or questions??
For Virtual Connect 3.x, you no longer have the option to select “Static” for “Login Distribution” and it gets set to “Automatic” and that is why “Login Distribution” it is no longer a viewable field in the GUI.
If you are trying to “Re-Distribute” the current logins, click SAN Fabrics in the left VC Manager navigation window and left-click to select the SAN Fabric row, then right-click to display a menu, and then select Redistribute Logins.
The “Login Re-Distribution” is “Manual” for VC-FC 4Gb, VC-FC 8Gb/20, and VC-FC 8Gb/24. The “Login-Redistribution” can be configured for “Automatic” on VC FlexFabric modules only.
So let’s say you have only 2 uplinks in a Fabric running VC 3.x, the logins would be distributed between those 2 ports automatically as logins occur. Theoretically out of 16 servers, 8 logins would be on Port 1 and 8 logins on Port 2.
Now you go into the VC GUI and add 2 more uplinks to the Fabric and apply that setting. The Servers will not use ports 3 and 4 until they logout and re-login to the Fabric. To force the “Re-Distribution” you can select the button on the Fabric called “Redistribute Logins” and it will force them to logout and re-login which will balance the FC traffic across all 4 ports without having to wait for the servers to logout at some point in the future.
With FlexFabric modules only, the option is allowed for “Automatic” Login Re-Distribution which means if you add 2 more ports to the Fabric, it will force the logout/login and balance on the fly, without having to select the button.
In the VC 3.x GUI if you create a Fabric with a port on a FlexFabric module, you will get the option to show “Advanced Settings”. This is where you can modify the “Login Re-distribution” to Manual or Automatic.