During SLES install over NFS, locking is not available

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Environment

SUSE Linux Enterprise Server 10

Situation

During a SLES install over NFS, the status daemon (kstatd) is disabled, meaning that NFS file locking cannot be done. While this does not interfere with a standard install, this can cause trouble for those who use autoyast to set up additional customized installation steps, involving NFS mount points beyond the one established for the install source materials.

For example, if an additional NFS mount was done to write data in a remote database during the install, and the client being installed wanted to get locks over that NFS mount, it would fail to get those locks and receive errors.

Resolution

To workaround this, an NFS mount done during the install procedure can include the 'nolock' parameter. The NFS mount of the install source materials is already done this way. The'nolock' parameter means that when an application on the installing machine asks for a lock, the NFS client code will respond that the lock has been successfully obtained, even though no lock request has actually been sent to the remote NFS server.

This will allow an application which asks for locking to proceed. However, this should be used with caution. If the application is accessing a database that is accessed by multiple clients simultaneously, data loss could occur, since more than one system could think they have locks on certain areas, when they really do not.

If true NFS locking is needed, then the operations in question should be put off until the install is fully complete and the system is rebooted. Note that one reboot already occurs during the install procedure, but an additional reboot after the install is 100% complete will be needed before true locking can be done.

Disclaimer

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