Determine the active Controller on EVA3000?

[Christian Reiter]

Hi!

I am in need to determine the active controller of an EVA3000 with old Active/Passive Firmware Setup.

I have to do a restart of the storage system tomorrow to due a relocation of the eva to a new builing. There are several legacy linux systems connected to the system which are only connected by one path (without secure path or mpio), so i have to ensure that the same controller is active when the eva gets up again as when it was shutdown.

Thanks for your help in anticipation!

christian

[Uwe Zessin]

Both controllers are 'active' - what you need to find out is the "controller ownership"/ the "managing controller" for a single virtual disk. This can be seen in recent versions of CV-EVA. If the system has been set up properly, there is a failover/failback path preferrence on the affected virtual disks.

[Christian Reiter]

Thanks for your fast response, Uwe!

I thought that with old EVA3000 VCS-Versions there is only one active controller and the other one is waiting for the first one to fail (Active/Passive). Isn't that true?

Certainly I've set a failover preference in my vdisks, but I wanted to be on the safe side (I know that I've got a weird setup, but for reasons out of my area of responsibility I am not able to "repair" this config).

thanks,
christian

[Uwe Zessin]

No, that is not true. Both controllers do work at the same time and can be managing (for different) virtual disks since version 1.

active/active and active/passive can mean slightly different things on different arrays.

[Christian Reiter]

Oh, I'm a little bit confused now...

Would you mind explaining the differece between A/A and A/P in the case of EVA3000?

[Mark Wibaux]

This is an extract from the VMware iSCSI config guide, however it still applies in general to all arrays (apart from option 3 which is really iSCSI specific)
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An active/active disk array, which allows access to the LUNs simultaneously through all the storage processors that are available without significant performance degradation. All the paths are active at all times (unless a path fails)."

An active/passive disk array, in which one storage processor (SP) is actively servicing a given LUN. The other SP acts as backup for the LUN and can be actively servicing other LUN I/O. I/O can be sent only to an active processor. If the primary SP fails, one of the secondary storage processors becomes active, either automatically or through administrator intervention.

A virtual port storage system, which allows access to all available volumes through a single virtual port. These are activeâ active storage devices, but hide their multiple connections though a single port.
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Strictly speaking the EVA is an Active/Passive system as each LUN can only be actively "owned" by one controller. However each controller can "own" different LUNs so that both controllers are actually doing work. A real Active/Passive array was the original versions of the MSA1000 & MSA1500. In their case one controller just sat their waiting for the primary to fail no host-to-SAN/SAN-to-host data passed through the "Passive" controller.

Pinching an explanation from another blog (http://www.yellow-bricks.com/2009/02/10/load-balancing-your-luns-on-activeactive-sans/)
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The arrays from the EVA family are AAA arrays. In an Asymmetric Active-Active both controllers are online and both can accept IO, but one controller is assigned as the preferred (owning) controller of the LUN. The owning controller can issue IO commands directly to the LUN. The non-owning controller, - or to make this text more legible - proxy controller can accept IO commands, but cannot communicate with the LUN. For example, if a read request reaches the array through the proxy controller, it will be forwarded to the owning controller of the LUN.

If the array detects in 60 minutes that at least 2/3 of the total read request to a LUN are proxy reads, ownership of the LUN is transitioned to the non-owning proxy controller. Making it the owning controller.
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Hope this helps

[Juan B.S.R.]

Hi.
You can know which one is the master controller through the OCP panel in front of both EVA controllers. Scroll down the menu until you see "Mastership Status" inside "System versions" but I cannot remember exactly the location.
I hope this can help you.
Bye.

[Mark...]

Hi

Ref Jaun comment:
This is correct for EVA 4x/6x/8x00.
For the EVA3/5k there is no mastership menu option. To find the master controller then when you go into the "Versions" menu if you "read" the ocp it will tell you which one is master or slave.
For a 4400 use the WOCP.
You can also use cvutil which will tell you the membership status.

Mark...

[t3_chris]

Thanks a lot to all who helped!

How do i assign points heres?

[Uwe Zessin]

Only the original account (ChristianReiter) who created the thread can assign points.