iSCSI storage LUN design in HA planning

[SubXiao]

Environment:

- 2 x ESX hosts (H1 and H2), 1 x iSCSI Array, 2 VM each on ESX host

- 2 x iSCSI LUN (LUN0 and LUN1)

Question:

How to assign those two LUNs to H1 and H2 physical hosts?

1. Assign LUN0 to both H1 and H2, so that during failover, both H1 and H2 has access to same LUN or

2. Assign LUN0 to Host 1, while LUN1 to Host 2, will it works if one of physical host fail, the VMs will migrate over to the other host?

Any detail setting need to be aware of?

Thanks a lot!

Sub

[marcelo_soares]

All hosts must see all luns in order to make HA to work. You will not have the VMs powering on in the other ESX if it cannot see them.

I think this is your question, don't it?

Marcelo

[SubXiao]

Thanks for the response.

Which solution from my post will work, number 1 or number 2?

I understand the LUNs must be seen by both physical host. Does it means that both physical hosts will access the same datastore (one LUN can only create one datastore?)

The other further question will be is it possible to create multiple LUNs for one HA with 2 hosts? What will it looks like if that is possible?

Cheers,

Sub

[marcelo_soares]

Solution number 1, I think. The fact is that you will present both luns to both ESXs. If you create a datastore in 1 LUN, the other ESX will automatically see it just with a rescan on the iSCSI hba.

You can have multiple LUNs presented to ESX Servers, I think up to 256.

The best is to have one datstore per LUN, but you can create more if you want - manually with vmkfstools.

Marcelo Soares

Unix Admin - VCP3

[azn2kew]

Make sure you have multiple iSCSI paths to your target and present the LUNs to all ESX hosts so they can utilize VMotion, HA features. In case one path failed, it will failover to other and still functional on storage perspective. Xtravirt Virtual SAN Application (VSA) is has pretty good high availability on storage feature you can check out for free. www.xtravirt.com

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Stefan Nguyen

VMware vExpert 2009

iGeek Systems Inc.

VMware, Citrix, Microsoft Consultant