Using Network Attached Storage with SAP ASE

There are a couple of special considerations to take into account when configuring LifeKeeper to use an NFS file server (Network Attached Storage) as cluster storage.

Use the Recovery Kit for Network Attached Storage

The optional Recovery Kit for Network Attached Storage (NAS) is required when using an NFS server as a shared storage array with LifeKeeper for Linux. Install the Recovery Kit for NAS (and a license) on each cluster node. See the Recovery Kit for Network Attached Storage documentation for more details.

Possible Error Message

When using Network Attached Storage (NAS) with SAP ASE, you may experience SAP not restarting following a failover due to a system crash. The SAP error log should indicate the cause of the error.

SAP ASE 15.x

00:00:00000:00000:2011/05/09 16:08:51.66 kernel Adaptive Server Enterprise(Developer Edition)
00:00:00000:00000:2011/05/09 16:08:51.66 kernel basis_dlock: file ‘/s10/sybase-data155/data/master.dat’ already in use by an ASE
00:00:00000:00000:2011/05/09 16:08:51.66 kernel kdconfig: unable to read primary master device
00:00:00000:00000:2011/05/09 16:08:51.66 server kiconfig: read of config block failed

This indicates that the SAP dataserver has set an NFS lock on the file “master.dat” on the NFS file system that is being controlled by LifeKeeper. The lock was not cleared by the system crash, so LifeKeeper is unable to bring the dataserver back into service. SAP thinks that some other process is using the master.dat file.

Solution

To fix this, mount the NFS file system that will hold master.dat with the “nolock” NFS option before the File System resource is created. By default, NFS allows file locks to be set. If the “nolock” option is used before resource creation, LifeKeeper will pick up this option and use it each time it brings the file system resource in service. Since LifeKeeper will be controlling access (from the cluster nodes) to the file system containing master.dat, the lock is not typically critical. The NFS mount options used during testing were “rw,sync,tcp,nfsvers=3,noac,nolock”.

It is not necessary to use the “nolock” on other file systems used by the SAP resource hierarchy such as the file system where the SAP ASE binaries are located.

If the NAS File System resource has already been created without the “nolock” option set, use the following procedure to change the mount option:

1. Using the LifeKeeper GUI, take the file system resource that needs to be changed out of service. This can be done from the LifeKeeper GUI putting the pointer on the file system resource and doing a right mouse click, and select "Out of Service" from the drop-down menu. This action may take parent resources out of service as well.

2. Confirm the "Out of Service" action and allow the process to complete.

3. Once the file system resource is out of service, you can put the pointer on the resource and do another right mouse click, and from the drop-down menu, select "Change Mount Options".

4. In the popup window, add "nolock" to the line of options, and click "Set Value." You will need to repeat steps 3 and 4 for each node in the cluster.

5. Bring the NAS File System resource back in service by doing a right mouse click, and selecting "In Service".

6. The File System resource’s property panel should now reflect that "nolock" is one of the current mount options.