Changing failover mode for ESX host

Question

Hi,

I mistakenly configured the 3 ESX hosts we've just deployed for a project with Failover Mode "1" set for the host properties on our Clariion CX4-240 (Flare v28), I'd always done it this way for ESX v3.5 hosts and didn't realise it had changed with ESX v4 (vSphere). I'm now looking to use the Failover Setup Wizard to change each host to Failover Mode "4" however we now have active VMs running that I can't get downtime for. Is it safe just to put a host into maintenance mode, run the wizard, bring the host back up and repeat? I'm just concerned that during the re-config I'm going to have different hosts connecting via different Failover Modes to the same LUN at the same time, is that an issue (even if for a short time)?

Thanks,

Nick

RobertDudley · Accepted Answer

NickF  If you are looking to take advantage of the ALUA behavior available then you would need to change the fail over mode to 4.  If your host HBA's are set to MRU and you are using the Clariion in the default active/passive configuration then failover mode 1 is correct.

harshab · Answer

CLARiiON with Asymmetric Logical Unit Access (ALUA) mode is

supported beginning with ESX 4.0. For CLARiiON, the default

failover mode for ESX host is failover mode 1 with the storage type as

Active/Passive. When ESX host is registered in failover mode 4,

ALUA mode is enabled. In such a case, the CLARiiON array will

behave similarly to an Active/Active array. The ESX server applies

the "Fixed" policy to CLARiiON devices in a VMware native

multipathing environment by default.

Note the following:

◆

ESX 3.5 and earlier do not support ALUA mode

◆

ESX 4.0 with VMware native Multipathing fixed policy supports

Flare 04.28.00.5.704 or later in ALUA mode

◆

ESX 4.0 with PowerPath /VE supports Flare 03.26 or later in

ALUA mode

Phuzzi · Answer

Thanks for the replies. I think I was getting confused by the Clariion/VMware integration guide and thinking you had to run in Failover Mode 4 with ESX 4 to be supported but I guess it's just an option. I think our Flare is too old for that anyhow (04.28.000.5.504), although we do have a request in currently to get it patched.

As it looks like I'm sticking with Failover Mode 1 for the ESX hosts (with MRU policy) is that going to cause problems when I have a Windows 2008 R2 VCB server connecting to the same LUN as the ESX servers? From the Windows host integration guide it looks like you need to use Failover Mode 4 for Windows MPIO native multi-pathing (and this seems to work for a SQL cluster we have SAN attached, although I'm a bit concerned now regarding the Clariion Flare version). I'll be disabling automount etc. so I don't trash the VMFS but I'll still have the ESX hosts connected via Failover Mode 1 and the Windows host connected via Failover Mode 4 to the same LUN, is that going to cause any issues or am I worrying too much about how much effect Failover Mode configured on a host has on a LUN?

Thanks,

Nick

CLARiiON

Changing failover mode for ESX host

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