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Windows file servers are protected by monitoring key processes and file systems. When a file server or dependent resource is detected not to respond, LifeKeeper will optionally attempt to undertake a local recovery on the server (depending upon configuration). If this recovery fails, then the file server is recovered on the remote server. In order for failover to take place, all nodes within the cluster need to be able to access the same data files (i.e. the data the file server is sharing with the end users). There are two ways data can be available to all clients, either using a shared storage solution (for example SAN, NAS, SCSI), or LifeKeepers Data Replication add on can be used to replicate data between servers over a LAN or WAN.
Shared storage allows for a larger cluster to be created, and can also scale further.
Data Replication on the other hand, allows the two nodes to be any distance apart and normally reduces the cost of the solution. It can therefore be used to produce an identical copy of the data on a remote site or different server, effectively enhancing availability and reliability by giving you redundant storage in separate locations
As illustrated in the image below, LifeKeeper can run in an Active/Active configuration if necessary. Active/Active configurations allow all nodes in a cluster to be active, allowing maximum hardware utilisation while still providing redundancy.
Further down Active/Standby configurations are discussed with the Data Replication option
In the above illustration two nodes form the cluster. Each node runs an IIS web server as well as sharing files to a network. Both nodes have access to the same shared storage unit. In the event of one node failing, the other node is capable of running all four applications, therefore ensuring continuity of service.
LifeKeeper data replication replicates data from a local disk located on an active server to a local disk located on a backup server. When recovery on the backup server takes place, data is up-to-date due to the replication that has already taken place.
Using the data replication feature, it is possible to undertake remote failover to a remote site. This normally involves the use of asynchronous data replication for performance purposes. LifeKeeper is used to initiate and coordinate the failover to the remote site.
The data replication software provides numerous additional features, for instance is is possible to pause the mirror and undertake a backup on the remote copy of the data, and then un-pause the mirror without suffering a full resynchronisation of the data. Further information on this can be found here.
A Java GUI simplifies administration, configuration and management of the failover and data replication process. This can be done via the console or through a web browser.
For a seamless recovery of your Windows File servers, SteelEye Life Keeper from Open Minds guarantees to provide you with a complete disaster recovery solution ensuring that you maintain business continuity. Our high availability solutions will grant continuous data protection providing data replication as well as the monitoring of all your Windows File servers to ensure failover through the Java GUI.
In fact, the solution was better than we had expected. We had planned a local backup and a remote backup at the DR site. But the solution worked so well, we decided not to have the local backup.
Charles Hornung, New Star Asset Management
