The snapshot utility that you select must use consistency groups to ensure consistent data across data sets and must have the ability to briefly suspend writes to database files and logs.
Storage vendors provide snapshot capabilities that span multiple data volumes and logical unit numbers (LUNs) by using consistency groups, also known as protection groups. With these capabilities, they can capture a snapshot very quickly (almost instantaneously) across multiple data volumes or LUNs. This is a key technology for enabling online backups because it preserves relationships and references between data sets. It is also important to create the snapshots rapidly in order to both minimize the impact on the system and its users and to ensure that the data is consistent across data sets.
For IBM® System Storage® N series products based on NetApp technology, the NetApp family of snapshot products, which includes Snap Creator, SnapDrive, Snapshot, SnapManager, and Protection Manager, can capture a collection of storage area network (SAN) LUNs for databases, NFS or CIFS network file system volumes, and WORM (SnapLock) volumes in a coordinated point-in-time snapshot. Consult with your storage vendor for equivalent snapshot capabilities if you use other storage products for your FileNet® P8 system.
Another key technology that enables online backups, this time involving databases, is the ability to briefly suspend writes to database files and logs, while still allowing database clients to perform database operations. This ability briefly stops database changes at the disk level, while still accepting database operations from client applications. This is different from putting the database in read-only mode because writes are still accepted, just not written to disk. Writes are effectively queued until the suspension is lifted, stalling the completion of database transactions without completely shutting down the database or its clients. Some key FileNet P8 operations, notably content-related operations like adding new documents, stall when database writes are suspended in this way because of the manner in which FileNet P8 uses database technology to make content operations reliable and robust. New database transactions cannot complete while writes are suspended. The net effect of briefly suspending database writes is to stop database file and log changes and indirectly slow down other FileNet P8 operations that depend on database transaction completion. Suspending database writes reduces the overall rate of change of the data and places the database in a relatively clean state, which improves the chances of capturing all the data sets in a consistent state, even if the snapshot operation is not perfectly aligned in time across all the data sets.
For IBM DB2® databases, use the SET WRITE SUSPEND command during online backups. For more information about this command, see the SET WRITE command topic in the DB2 online documentation. Consult with your database vendor for an equivalent write suspension feature if you use Oracle or Microsoft SQL Server instead of DB2 for your FileNet P8 database.