[OmniOS-discuss] Active-Active vSphere

[Rune Tipsmark]

so to simplify, say we have one esxi host that has two FC ports, one omnios/zfs server has two FC ports as well.
Should it run ALUA with Round Robin instead of the default ALUA with MRU (most recently used). RR has traffic on both paths (says Active I/O on both) and MRU only on one...


-----Original Message-----
From: OmniOS-discuss [mailto:omnios-discuss-bounces at lists.omniti.com] On Behalf Of Saso Kiselkov
Sent: Thursday, November 27, 2014 12:47 PM
To: omnios-discuss at lists.omniti.com
Subject: Re: [OmniOS-discuss] Active-Active vSphere

On 11/27/14 3:35 PM, Rune Tipsmark wrote:
> Hi guys,
> 
> Does anyone know if Active/Active and Round Robin is supported from 
> vSphere towards OmniOS ZFS on Fiber Channel?

The short answer is: yes, but you wouldn't want to employ Round-Robin on it. A ZFS pool can only be imported on a single node, never simultaneously on two or more. However, using ALUA it's possible to make the LUs on it visible from two OmniOS nodes - this is NOT round robin, though. The initiator will see two paths to the LU, but only one should be active at any one time (the one that has the pool holding the LU imported). Access to the LU over the secondary target will be possible, but slow. Upon failover, the secondary would grab the pool and become the preferred ALUA path, so it all works out OK. Google "ALUA" for more on the theory behind it.

It is a complicated to set up, though, so be aware of that.

Cheers,
--
Saso
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