LifeKeeper for Linux NAS Recovery Kit
The primary focus of the LifeKeeper for Linux NAS Recovery Kit is to offer LifeKeeper users an alternative storage method to shared storage and data replication.
The NAS Recovery Kit enables the creation of LifeKeeper resource hierarchies on LifeKeeper protected servers or clients that have imported (mounted) an exported Network File System (NFS) from either a Network Attached Storage device or an NFS server in the cluster. When a failure is detected on the node in the cluster where the exported file system is mounted, the NAS Recovery Kit initiates a fail over to the predetermined backup node.
Therefore, once the exported file system is mounted on a LifeKeeper server or client, it can be fully utilized as an additional storage basis for LifeKeeper hierarchies.
When you elect to use an exported file system as a storage medium, LifeKeeper does not require you to protect the server where the file system is exported. However, to achieve a greater degree of availability, users are encouraged to use the LifeKeeper for Linux NFS Server Recovery Kit to protect the server from failure where the file system is exported.
Resource hierarchies for the NAS Recovery Kit are created using the currently existing File System Recovery Kit available with the LifeKeeper Core product (steeleye-lk package).
While the NAS Recovery Kit delivers several advantages, the two most significant advantages are the elimination of the need for costly shared-storage devices and the capability to have multi-node cluster configurations.
NAS Recovery Kit Restrictions
- This version of the NAS Recovery Kit does not include support for a local recovery when access to the NAS device fails. When a failure is detected, the default action is to initiate a transfer of the hierarchy to a backup server. Depending on the makeup of the resource hierarchy, this action can result in hung processes. To avoid hung processes, the default action can be changed to halt the server and force a failover to a backup server. To change the default switchover behavior, alter the setting of LKNASERROR in the LifeKeeper defaults file. See the section Configuring the NAS Recovery Kit later in this document for more discussion on LKNASERROR.
- The NAS Recovery Kit does not provide protection for your Network Attached Storage device. The objective of this kit is to expand LifeKeeper storage options into the Network Attached Storage arena.
- The NAS Recovery Kit does not permit the NFS file system to be mounted more than once on different mount points. Attempts to create hierarchies when the file system is found in the /etc/fstab file multiple times will fail.
- File systems to be protected by the NAS Recovery Kit should be mounted using the IP address rather than the host name (for example, 100.99.100.9/dir instead of server1/dir). This will avoid potential DNS or host file lookup problems. Mounting via host name will result in a “bad mount” being detected, after which LifeKeeper will unmount and re-mount the file system using the IP address. The unmount process could kill processes that are currently using the mount point.