You can refer to its user manual:

Default owner of a LUN

Hi,

Thanks for your response, but it does not seem to be correct.

I am using VNX7500 05.32.000.5.209

I created 10 LUNs in one operation on SPA, I then created 10 LUNs individually using (auto assign) the 10 LUNs were assigned to SPB.

It's better if you leave them to Auto, cause SPs can handle them mutually, if one can't handle the workload the other can respond to I/Os. If you are assigning to them to both SPs manually then have to look at the size and I/O workload handled by them on all those LUNs.

Thanks

Rakesh

Hi Rakesh,

Thanks for responding.

Yes, agreed, I had already thought of that.  But I'm still looking to find what the behaviour of auto assign is.

Regards

There are 2 cases of auto-assign :

1. When an SP fails all the I/Os will be redirected to the other SP, cause the remaining SP has to look after the entire LUNs' requests.

2. If the I/O flow increases & let's say SP-A owns that particular LUN & is unable to serve the request, the same is done by SP-B (in case of trespassing has taken place, which is an obvious scenario).

In both of the cases we only have to set the power path policy correctly. Normally ALUA (Mode-4) & in case of HP-UX EMC recommends to go with Mode-1, to get the I/Os served continuously even if few path fails.

I still recommend you to go with Clariion best practices for load-balancing.

Thanx

Rakesh

Hi Rakesh,

Thanks for that info, but that's not what I'm looking for.  All I'm looking for is information on how the VNX auto assigns to an SP when you create a LUN.  i.e will it go to SPA or will it go to SPB and it what circumstances will it go to SPA or to SPB.

As stated before:

I am using VNX7500 05.32.000.5.209

I created 10 LUNs in one operation on SPA, I then created 10 LUNs individually (consecutively) using (auto assign) the 10 LUNs were (auto) assigned to SPB.

so for example; if there are more LUNs on SPA than SPB, when you create individual LUN's using auto assign should the VNX add the new LUN's to SPB until the number of LUNs is balanced with SPA. (as this seems to be the behaviour).

I'm trying to understand:

1. Is that the expected behaviour?

2. Where is this behaviour documented?

3. Are there any other assignment behaviours I need to be aware of?

Regards

Stuart

Yes, that's done by system itself, I mean by FLARE code. There could be one lower or higher like this : if a system has 9 LUNs, SP-A owns 5 LUNs created within the system, next SP-B will own 4 LUNs, & the 10th LUN will be automatically owned by SP-B, in this case.

https://www.emc.com/collateral/hardware/white-papers/h5773-clariion-best-practices-performance-availability-wp.pdf

Thanks

Rakesh

Hi Stu,

i just doublechecked it with a VNX2.

I added 12 LUNS to SPA. OK

Then i added 10 LUNS with AUTO. OK

The 10 AUTO LUNS were distributed between SPA and SPB the way Rodger wrote

FLARE 32, VNX-7500, so it comes under VNX-1.

Thanks

Rakesh

You can refer this one as well :

http://www.codestone.net/resources/files/h17371-emc-clariion-high-availability-best-prac.pdf

sebbo wrote: Hi Stu, i just doublechecked it with a VNX2. I added 12 LUNS to SPA. OK Then i added 10 LUNS with AUTO. OK The 10 AUTO LUNS were distributed between SPA and SPB the way Rodger wrote RAID Group IDs Default LUN owner Odd-numbered SP A Even-numbered SP B

Where is load balancing in this case (As you are using VNX-2 with MCx, its fine, but hardware will still be hardware). You have added 12 LUNs to SPA which is fine. You created again 10 LUNs which are distributed between both. Now, SP-A owns 17 LUNs and SP-B 5 LUNs. Which one would work better is it the second one? I believe. Rodger is right that it will assign LUNs like odd & even formula, if you use Auto-assignment.

The question is how system behaves with it .....

Thanks

Rakesh

Just doubleckecked with VNX1. Sorry Rakesh but it works as designed.

You may wish it your way but it is as it is.

LUN ID 1 - 11 created with Default Owner SPB

LUN ID 12 - 16 created with Default Owner AUTO

If one SP is overloaded with I/Os and the other is doing nothing you should look at getting another Service Partner (-:

There is still a reason why there are educated technicans.

I'm not saying it doesn't work. It works even with Clariion. But what we are discussing is something I mentioned above :

"The question is how system behaves with it ....." (in case if one SP is overloaded with I/Os than the other or if one SP fails....?)

Thanks

Rakesh

Hi Everyone,

When I say behaviour, All I am referring to is how the VNX decides which SP to auto assign to.

Everyone also seems to be missing one important aspect of my original test:

1. the first 10 LUNs were created at the same time using the inbuilt VNX functionality to create 10 LUNS and name as requested, these were manually assign to SPA.  The result was 10 luns being assigned to SPA

2. I then created 10 LUNs INDEPENDANTLY (not using the VNX functionality to create 10 LUNs in the same operation) every LUN I created using auto assign. The result was all 10 LUNs being auto assigned to SPB (this is fact)

The information i'm after is:

1. Is that the expected behaviour?

2. Where is this behaviour documented?

3. Are there any other assignment behaviours I need to be aware of?

Regards