Shared file system on cx4/AIX

you can't do it with jfs2, have to have a file system that supports concurrent access like GPFS.  If block storage is not required you could use NFS as a way to provide "shared" pool of space.

Thanks, I wonder if it makes sense to put the this "shared" file systems on our NAS filer.  It sounds like we could then use NFS and mount it to multiplie hosts.  I wonder what happens when both hosts try to write to it at the same time???

The other option is to find out more about GPFS.  I don't know if this comes free with AIX 6x or if we need to purchase.  I would like to test it out for free before hand.

BradRondeau wrote: Thanks, I wonder if it makes sense to put the this "shared" file systems on our NAS filer.  It sounds like we could then use NFS and mount it to multiplie hosts.  I wonder what happens when both hosts try to write to it at the same time???

the question is if NAS storage will provide adequate performance for your application requirements. Regarding concurrent access ..NFS handles file locking, especially NFS v4.  I think GPFS is part of their cluster software suite ..i doubt it's free ...we are talking IBM here

Great point - we will meet with users this week to get very detailed requirements.  We may have the situation that you suggest, where the first LPAR needs high performance but the second LPAR needs access only occasionally.  So, maybe we just create the JFS2 file system on the first host (on CX4) and then create an NFS mount from the other server/LPAR to the same file system.

Sounds like it may work.  I'm guessing that NFS would keep updates from colliding - I've never set this up before.  Looks like I can use AIX commands like mknfs, mknfsexp, mknfsmnt to set this up.

In thinking about this a little bit more I think a real starting point might be to go back to the user requesting this additional functionality and get them to define their requirements. You can waste a bunch of time trying to figure out how to do something that isn't clearly defined, or you can have them really think about what they are asking and why. Once you have a clear understanding of what is required it might become obvious what the best option is. It might even become obvious that the end user has no idea what they really want and they are just wasting your time. You never know until you ask!

NFS would absolutely manage the file access to prevent conflicts.

As for how you actually do it, I'm a Windows guy and couldn't begin to tell you how to actually accomplish this on a Unix host. I can do it on Windows, but I can only give you ideas on Unix and someone else will have to tell you how to actually get there :-)

One of these days I'm going to have to take the time to learn how to do stuff on Unix. So far I've had a dedicated Unix team who won't let us touch their hosts, but needs regular direction on what they should be doing (Storage related). I never actually get to get my hands dirty with it so I don't actually get to learn it on the job.

This is a good article on NFS. In version 4 there are more options available for allowing concurreny.

http://www.redbooks.ibm.com/abstracts/sg246657.html

HACMP is another option as you can cross mount file systems. However, HACMP is not a free software like NFS.