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EVA VDISK creation and preferred path options

EVA VDISK creation and preferred path options

Hello. I am inquiring about EVA8000 VDISK creation and the various preferred path settings (no preference, failover only, failover and failback) and the considerations around each one. We have two EVA8000's which we are now testing prior to going into production. Many VDISKS will be replicated via CA using DR Groups, some VDISKS will not be replicated. Hosts are Tru64 (Native failover software), Solaris 9 (DMP) and Windows (MPIO). Looking for some additional information.

Thanks,
Dave
12 REPLIES
Luk Vandenbussche
Honored Contributor

Re: EVA VDISK creation and preferred path options

Hi Dave,

I have installed several EVA yet.
I always take the option no preference on the EvA.

I balance the load on the servers through securepath or native failover if the os can handle is.

When I use mpio i also take the default option. I never had performance problems
Ivan Ferreira
Honored Contributor

Re: EVA VDISK creation and preferred path options

The command view User Guide has all information that you need. Basically:

- If the OS uses secure path, like hp-ux, windows, linux, the only supported preferred path option is "failover only"

- If the OS does not requries secure path, like Tru64 or OpenVMS, you can select any failover method (failover only/failover and failback).

- All copy sets in a DR group must have the same preferred path configuration, because all must failover at the same time.

Then, you can use evaperf to verify the controller that servers a particular vdisk, and the controller utilization.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Re: EVA VDISK creation and preferred path options

None of my hosts will be using SecurePath on the EVA8000's.

So if I choose no preference, will the controllers load balanace themeselves and make sure any copy sets that are needed for CA are on the proper controller?
If I have several LUN's in a DR Group is there any disadvantage to using no preference as opposed to the other choices?

Ivan Ferreira
Honored Contributor

Re: EVA VDISK creation and preferred path options

In our experience, setting no preferrece does not balance the VIDSK between the controllers. All units are presented to the first booted controller. So, is better if you set the preferred path manually.

The DR group won't have problems if you configure no preferrence, but you will have better performance if you distribute the load between the controllers.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Re: EVA VDISK creation and preferred path options

Has your experience with the no preference settings and load balancing been more on EVA 3K5K or 4K6K8K or both?
Ivan Ferreira
Honored Contributor

Re: EVA VDISK creation and preferred path options

We use EVA5K, and soon will install EVA4K. All our systems are Tru64 Unix with TruCluster.

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Alzhy
Honored Contributor

Re: EVA VDISK creation and preferred path options

For HP-UX Vdisk clients that will use SecurePath - use Path Preferencing. Divvy up the LUNS accross the controllers/paths...
Hakuna Matata.

Re: EVA VDISK creation and preferred path options

I guess what I am getting at here is when you have two EVA8000's in a Continuous Access setup with
Tru64
Solaris
Windows
is it best to use "no preference" and let the array manage preferred paths, or is it advisable to plan out which preferred path setting will be used on each LUN.
Alzhy
Honored Contributor

Re: EVA VDISK creation and preferred path options

In that case, no preferencing since the client OS'es mentioned do have native pathing support as mentioned.
Hakuna Matata.
Ivan Ferreira
Honored Contributor

Re: EVA VDISK creation and preferred path options

If you set to "no preferrece" they won't be fairly balanced. Manually set the preferrence, also, you must know that when you set the preferred path for any member of a DR group, all other vdisks in the same DR group automatically configures the same preferred path, you don't have to do it manually. (I just tested).
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?

Re: EVA VDISK creation and preferred path options

Good info, thank you.
Ivan Ferreira
Honored Contributor

Re: EVA VDISK creation and preferred path options

Dave, take a look to:

http://forums1.itrc.hp.com/service/forums/helptips.do?#33
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?