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Isode M-Vault: Reliability & Fault Tolerance

Reliability

M-Vault utilises a high-performance transactional database. This provides a high level of assurance that hardware, operating system or application software failures will not corrupt a directory server database. It also enables the establishment of an on-line back-up regime for a directory service that will support both simple-recovery and disaster-recovery scenarios.

Hot Backup

M-Vault includes tools for backup of the databases while the server is running, so the directory service can provide uninterrupted service.

Database Recovery

The underlying on-disk database is transactional. This means that in the event of a system-crash or hardware failure then the database is recoverable once the machine and disk database have been brought up again.

Fault Tolerance

Data can be replicated using X.500 DISP (Directory Information Shadowing Protocol). This enables the various servers in a distributed directory to hold local copies of data held elsewhere. This ensures that data is available if one server in the network goes down. This scheme can also be used to configure a failover cluster, ensuring that mission critical data is always available.

Replication

Replication of data in a directory is essential to achieve robustness, performance and manageability. M-Vault implements the Directory Information Shadowing Protocol (DISP). The DISP implementation supports scalable replication.

Key features include:

• Total and incremental updates.
• Primary and secondary shadowing.
• Supplier and consumer initiated shadowing.
• Authentication of supplier and consumer.
• Scheduled and on-change updates.
• Flexible replication configuration.

Failover Clustering

M-Vault supports Off Site Hot Standby (Disaster Recovery) as well as fail-over clustering with backup servers containing data replicated (using DISP) from a master server. If the master server goes down the cluster will automatically switch in (fail over to) a backup server until the master comes back up again, thus ensuring continuous availability of the directory service and provided data.

Where write resilience is required Isode recommends the use of dual-ported disks to maintain a master database. If the primary server goes down, the clustering system immediately switches over to the backup.