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EVA4400 and ESX 4.1 mru failover

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inex
Super Advisor

EVA4400 and ESX 4.1 mru failover

I'm testing on a EVA4400 with ESX 4.1 mru failover settings. 4 luns, 2 on each controller. Luns are setup with path-A-Failover/Failback on controller 1, and Path-B-Failover/Failback on controller 2. During test i/o operations,I pulled out both host port cables on controller 1. All luns moved over to kcontroller 2 amd i/o continued. When I put back the cables in controller 1, all 4 luns remained on controller 2. I thought they automatically should have been moved to controller 1?

-inex
19 REPLIES
Uwe Zessin
Honored Contributor
Solution

Re: EVA4400 and ESX 4.1 mru failover

No, MRU means "Most Recently Used".

MRU is intended for active/passive arrays.

The EVA4400 is an (asymmetric) Active/Active array for which you should use RR (Round Robin).

RR (as well as MRU) are ALUA-aware (Asymmetric Logical Unit Access) which means they will talk to the controller which is owning the virtual disk.
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inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

In my scenario will the lun fail back, if I used round robin?

-inex
Uwe Zessin
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

How long did you pull the EVA controller host port cables?

The EVA does an implicit ownership transfer of a virtual disk if it detects that the majority of traffic goes through the other controller for about an hour.

With RR in ESX you should be able to force the ownership back to the intended controller using Command View-EVA. The ESX server should notice it after a short time and switch its active I/O paths to that controller.
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inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

The cables was out for 2-3 minutes, an the luns changed ownership at once.

I wanted the luns to fail back automatically. Maybe fixed path is the only way to do this.

-inex


Uwe Zessin
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

It's possible that the MRU failover code did trigger an ownership transfer - hard to say as not many people have access to these deep details.
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Mark...
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

Hi,
Under cv for each lun from the presentation tab you can set failover/failback (def is no preference) which should help.
Mark...
if you have nothing useful to say, say nothing...
Mark...
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

Hi
Sorry ignore last!
Just read your post again and you have it already!!
Mark...
if you have nothing useful to say, say nothing...
inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

I have 10 ESX luns and I want 5 on each controller. In case of controller problems, I want the luns to failback to their original controller. MRU does not do this. Maybe fixed path will.

-inex
Amar_Joshi
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

For the time being you can change the Vdisk settings to Path-A-FailoverOnly and that will bring back the LUN to controller A; then you can set it back to failover/failback again. I have seen this many times that EVA doesn't behave as expected for failover/failback settings and this is how I have been dealing with such situations.

Also, I would like to highlight that Round-Robin settings for ALUA compliance array (EVA4400) and OS (ESZX4.x) will allow hosts to send IOs to all ports (FP1 & FP2) of owning controller only. MRU settings will send the IO to only one port on the owning controller (either FP1 or FP2). You best choice for load-balancing is to use Round-Robin in conjunction with preferred Vdisk path settings.
inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

So if I set it to path-A-Failover/Failback and use fixed path, that will not do the trick either?

-inex
Uwe Zessin
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

Fixed uses one controller port only and is an individual setting for each ESX host. If one adapter path of one host fails, there is a chance that you can cause path thrashing.

Hm, didn't we have discussed this already?
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inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

We did, but I did not get complete answers for my questions
Uwe Zessin
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

Oh, sorry. I must have lost track with all those many threads.

No offense - I think it is better to write a small reminder in the original thread so it gets 'pushed up' and another notification mail is send out.
That way we don't lose the context and have to start from scratch again.

Did you get your question answered, now?
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Uwe Zessin
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

c02728798 - HP StorageWorks Enterprise Virtual Array (EVA) - Multipath Configuration Best Practices for Lun or Vdisk with VMware vSphere 4

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c02728798


Note:
2. Best practice for path policy (For more details, refer page 15 of the above document).

Avoid using Fixed I/O path policy with vSphere 4 and EVA.
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inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

I know this document. Fixed path is supported and I feel it is a better way of controlling the i/o on the different host ports. A downside is that it requires more configuration.
Jan Soska
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

Hello,
we use Eva4400 and Eva6000 under ESX, multipath set to RR, everything work as should.

Jan
inex
Super Advisor

Re: EVA4400 and ESX 4.1 mru failover

What version of ESX do you have?

Do you use Path-A-Failover/FailbackPath and B-Failover/Failback on the luns?

When running i/o on one lun, is all 4 host ports in use, or only the two host port on the managing controller?

Have you tested what happens with the luns if one controller fails? Do the luns fail back to the original setup, once the controller problem is solved?

thanks

-inex


Jan Soska
Honored Contributor

Re: EVA4400 and ESX 4.1 mru failover

hello,
we use ESX4u2 and ESX4.1 in mixed way, planning upgrade to ESX4.1 on all servers.
All disk are spread across Eva controllers with Failover/Failback settings.
As I remember, after recovering from failure disks go back to managing controller, but I will try it and come back as I am on vacation right now.

Jan
DirkRue
Occasional Visitor

Re: EVA4400 and ESX 4.1 mru failover

Hello together,

i think you´ll may can give me a hint, because you have some knowledge about HP EVA.

 

When you have two EVA 4400 with CA, is it possible to design an automatic failover for LUNs with vmware

without using  VMware Site Recovery ...? Just on the level of Storage and Controller.

 

We got a client (we didn´t install the EVAs) and they say, that after a failover the must presented manually the LUNs.

 

Thanx a lot.

 

Dirk