LUN Migration with Windows Cluster

[Sean Dale]

We have two Windows 2003 servers configured as a cluster. The cluster also runs SQL Server. There is a LUN for the database files and another LUN for the transaction logs. I created a new, larger LUN for the DB and another new, larger LUN for the logs.

Here is the question:
Can I use the LUN migration option on the SAN to move the data from the current LUNs to the newer ones? I don't know how a LUN migration would affect the clustered SQL Server environment. Also, would migrating to larger LUNs be a problem? The SAN is an EMC CX3-40F.

[IBaltay]

Hi,
according to http://www.dell.com/downloads/global/products/pvaul/en/cx3_infob.pdf there is an online LUN expansion feature. That means that you can expand the existing LUNs to its new sizes and then diskpart it on the Windows 2003 level. The preferred method in the MSCS cluster environmnent is to do it in the following steps:
a) bring the cluster resource (disk) offline
b) extend its capacity
c) extend the OS File system via the diskpart utility
d) bring the cluster resource (disk) online

[Sean Dale]

Thanks for the reply, however, I am not expanding the existing LUNs. I want to move the DB and logs from the current LUNs to new larger MetaLUNs. The database and log LUNs exist in a raid group used by another system. I want to know if I can use the EMC LUN migration to migrate the 2 currently used LUNs to the new larger ones I created without causing downtime to the SQL Server cluster.

[Steven Clementi · Accepted solution]

Sean:

The process can be very simple. Take a lok at the Cluster Recovery Utility from microsoft. It can be used to recover lost luns... or in your case... replace existing luns.

Copying the data is the easy part, getting the cluster to use the new luns is where people get stuck usually. Try the utility.

" http://www.microsoft.com/downloads/details.aspx?FamilyID=2be7ebf0-a408-4232-9353-64aafd65306d&DisplayLang=en "

Steven

[Sean Dale]

I don't know if this utility will work for me as the disks are not on a shared bus, but, on an EMC Clariion SAN. I may have to just present the new LUNs to the cluster and add them as cluster resources, shut down SQL Server, copy the data, rename the drives then restart SQL Server. I would really prefer to use the EMC LUN migration utility to move the data transparently, however, I do not know if moving the data to larger LUNs attached to a server cluster would work or not.

[Vasiliy Karpov]

As far as I know the other way around this problem is:

1) convert old and new LUN to dynamic volume
2) via Windows Disk manager - create mirror
3) break old one

This worked well in non-clustered environment. But I think it's not a big deal for a cluster since disk names wont change.

[Sean Dale]

Can I use Navisphere to migrate the data to larger LUNs then use diskpart to extend the volume on the Windows side?

[Vasiliy Karpov]

If Navisphere allows you to change LUN size without changing LUN id - you can enlarge LUN and then enlarge your dynamic disk on this lun. Otherwise it can't be done non-stop.

[R Loram-martin]

We do not use SQL in our enviroments. But this is the method for lun migration.

1 Create a new unbound lun of the required size.
2. right click the required lun in raid groups and select migrate.
3. choose the new unbound lun as a destination.

The new unbound lun will disappear and original lun will have a new tab of migration.

We use the lowest level of migration as this will not result in interuption of services to the server.

The migration done in this way will take several days and the time estimation on the migration tab is fairly accurate.

Once migration is finnished you can complete the disk expansion in windows.

[Sean Dale]

I added the new LUNs to the storage group, removed the SQL dependencies from the current drives, copied the data to the new drives then changed the drive letters. All is well. Thanks to all who responded.