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MQSeries.net Forum IndexGeneral IBM MQ SupportMulti-Instance & SAN not NFS

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Zappa
PostPosted: Wed Nov 10, 2010 5:08 am Post subject: Multi-Instance & SAN not NFS Reply with quote

Acolyte

Joined: 06 Oct 2005
Posts: 55
Location: UK

When creating multi-instance queue managers can the log & data shared storage be mounted from a SAN concurrently to both servers or does it have to be via an NFS server?
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JLRowe
PostPosted: Wed Nov 10, 2010 5:21 am Post subject: Reply with quote

Yatiri

Joined: 25 May 2002
Posts: 664
Location: South East London

Generally speaking, a SAN will not let you mount the same volume on more than one server, a SAN is working at a lower layer than the filesystem above it.

In the older style of clustering using active-inactive, a SAN volume would be failed over between two or more boxes using a product such as sun cluster or MSCS.

The newer shared queue managers operate at the higher file system level, and therefore two queue managers know how to interact & failover with each other using the filesystem as the means of communication. This is a lot easier to configure and get working as you are operating at the filesystem level.

Sorry, could explain it a bit more clearly, but hope you get the idea.
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Zappa
PostPosted: Wed Nov 10, 2010 5:54 am Post subject: Reply with quote

Acolyte

Joined: 06 Oct 2005
Posts: 55
Location: UK

Thanks for that, which is fairly much what I thought too but had to ask.

So the NFS server becomes a single point of failure if it is not HA'd and if it was HA'd then failing over the NFS share would cause an outage to the queue manager that is meant to be highly available.
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JLRowe
PostPosted: Wed Nov 10, 2010 6:00 am Post subject: Reply with quote

Yatiri

Joined: 25 May 2002
Posts: 664
Location: South East London

Yes, but the value premise is that it is a whole lot easier to make a filesystem highly avalable. I believe that the queue manager will keep retrying access to the file system, meaning it will bounce back up again when the file system is available.
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bruce2359
PostPosted: Wed Nov 10, 2010 7:47 am Post subject: Reply with quote

Poobah

Joined: 05 Jan 2008
Posts: 8363
Location: US: west coast, almost. Otherwise, enroute.

Quote:
So the NFS server becomes a single point of failure if it is not HA'd

Oddly worded.

NFS v4 is required for MI.

As I interpret the MI deployment (subject to misunderstanding) NFS software executes on both qmgrs in the MI. Each NFS instance monitors the filesystem lock - which the active qmgr owns until the active qmgr fails.
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JLRowe
PostPosted: Thu Nov 11, 2010 8:45 am Post subject: Reply with quote

Yatiri

Joined: 25 May 2002
Posts: 664
Location: South East London

Yes, but you still need a separate NFS server - which becomes the point of failure?
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mqjeff
PostPosted: Thu Nov 11, 2010 9:05 am Post subject: Reply with quote

Grand Master

Joined: 25 Jun 2008
Posts: 17447

JLRowe wrote:
Yes, but you still need a separate NFS server - which becomes the point of failure?


You need a SAN device or server of some kind as well, yes?
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Zappa
PostPosted: Fri Nov 12, 2010 3:34 am Post subject: Reply with quote

Acolyte

Joined: 06 Oct 2005
Posts: 55
Location: UK

The MQ systems mounting the file system be it NFS or SMB are both acting as the client to the NFS or SMB server. The shared filesystem could be sourced from a SAN which should have its own fault tolerances and redundancies and shouldn't be the SPOF.

I'm thinking that whatever serves this file share is the SPOF and will need to be HAd if you want the queue manager to be HA.
In my mind (please correct me if Im mislead) MI just moves the need for a HA cluster from the MQ servers to the file server/s.
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JLRowe
PostPosted: Fri Nov 12, 2010 7:26 am Post subject: Reply with quote

Yatiri

Joined: 25 May 2002
Posts: 664
Location: South East London

Yes, that's correct, it just 'pushes' the HA requirement down from the MQ app level to the file system level. But, the reason to do this is it's a lot easier to make a file system highly available.
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mqjeff
PostPosted: Fri Nov 12, 2010 8:21 am Post subject: Reply with quote

Grand Master

Joined: 25 Jun 2008
Posts: 17447

It's a lot easier to make a file system highly available and it's a lot more common to already have any NFS or SAN service already be highly available before MQ enters the picture at all.
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fjb_saper
PostPosted: Fri Nov 12, 2010 12:42 pm Post subject: Reply with quote

Grand Poobah

Joined: 18 Nov 2003
Posts: 19943
Location: LI,NY

mqjeff wrote:
It's a lot easier to make a file system highly available and it's a lot more common to already have any NFS or SAN service already be highly available before MQ enters the picture at all.

I think you meant contact admin service. As I remember it contact admin can attach the same volume to multiple boxes whereas SAN will limit the volume to one box...

But then what do I know I have to ask those network gurus every time...
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mqjeff
PostPosted: Fri Nov 12, 2010 1:08 pm Post subject: Reply with quote

Grand Master

Joined: 25 Jun 2008
Posts: 17447

NFS is something different.

Regardless of whether or not a Storage Area Network volume is mounted on a single computer at a time or not, the Storage Area Network controller/server can still be Highly Available (and usually is).
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