[Lustre-discuss] Lustre 1.6.6 to 1.8.3 upgrade + MDT hardware migration

Greg Mason gmason at msu.edu
Mon May 10 14:59:25 PDT 2010

I'm in the process of upgrading from Lustre 1.6.6 to Lustre 1.8.3, and there's quite a few goals I have when it's all said and done (in no particular order):

1. Upgrade to Lustre 1.8.3 (duh!)
2. Migrate MDT to better-suited hardware (from internal disk on an older system to a 2540 array hanging off a newer system). This is also moving from SLES 10 SP2 to RHEL 5.x
3. Upgrade X4500 OSSes from SLES 10 SP2 to RHEL 5.x
4. Upgrade the MGS to lustre 1.8.3 (most likely leaving on SLES 10 SP2)

We will be upgrading the clients in a few months, when we update our compute node OS image. The clients are running Lustre 1.6.7 currently.

I've been going through the Lustre manual, and it looks like the proper order of events for a 1.6.x to 1.8.x upgrade is:

1. Shut down the filesystem
2. Upgrade the MGS to 1.8, and mount it
3. Upgrade the OSSes, and mount all OSTs
4. Upgrade the MDS and mount the MDT
5. Mount the filesystem on the clients

I've also looked at operating mixed servers, and it looks like I can migrate and upgrade the MDT to 1.8 and upgrade the MGS to 1.8, while leaving the OSTs at 1.6 and everything will work fine. The idea here would be to eventually upgrade the OSTs at a later time, probably 1 at a time. The only problem is that this would mean I'm upgrading the OSTs after the MDT, which looks to be a no-no.

Some other misc. issues:
1. With the migration of the MDT to new hardware, do I need to do a writeconf if hostnames/IPs are staying the same? The new MDS hardware will be assuming the name and IPs of the old MDS hardware.
2. I've been asked if I can leave the filesystem mounted on all the clients during the whole upgrade. I could see this working for the OSSes, but not the MDT migration and MDT/MGS upgrade. Am I correct in this assumption? 

Does anybody have any advice on how to best accomplish the goal of Lustre 1.8.3 servers with Lustre 1.6.7 clients?



Greg Mason
System Administrator
Michigan State University
High Performance Computing Center

web: www.hpcc.msu.edu
email: gmason at msu.edu

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