NetWorker 9.0 Media database changes
In NetWorker 9.0, SQLlite replaces WiSS as the media database.
The new database features the following advantages:
- Object caching -- a targeted cache facility that operates independently of file system or database caching to maintain recently used objects in memory for subsequent requests.
- Parallel request processing (or multi-threading) -- database in previous versions of NetWorker was single-threaded, which means it could handle only one database request at a time. As a result, long transactions could delay the performance of any other transactions (for example, an operational request would have to wait until the bootstrap was completed). With multi-threading, the database can handle requests in parallel, so that the operational request would be picked up and handled immediately without requiring completion of the bootstrap.
- Request handling -- request that takes multiple seconds gets logged. You can choose to log all requests by setting dbgcommand to level 1 or higher in debug mode.
- Bootstrap compatibility -- mechanism being used for SQLlite is the same as for the WiSS database. If a problem occurs after upgrading, you can use a bootstrap taken from the previous system and recover that information directly into the SQL database. If you must temporarily downgrade NetWorker but already performed backups using NetWorker 9.0 that you want to maintain, you can perform a bootstrap and recover the media database into NetWorker 8.2, and that data will be recovered into the WiSS database.
The nsrmmdbd process handles the migration automatically during NetWorker startup after the upgrade. The database migration does not require any user intervention, and occurs in three stages (clients, volumes, and then save set records), with the daemon log indicating the beginning of each stage and logging any errors that occur. Once all data has been moved to the new database, NetWorker performs a cross check to verify the success of the migration. The migration process typically takes between 1-3 minutes but can take longer for very large databases (1 GB or greater).
On successful migration, the /nsr/mm/mmvolume6 directory gets appended with a timestamp to indicate that the directory is no longer active. You can keep this directory if you do not have a current bootstrap backup, otherwise it can be removed. The mmvolrel directory gets used as the new directory for the SQLlite database.
If the database migration does not complete, nsrmmdbd notifies you that migration has failed and the legacy WiSS database continues to run to process jobs until the migration is successful.
Note: EMC does not recommend hosting a media database on a remote file system, for example, an NFS file system. Not all systems handle file locking correctly, and this can also introduce access latency which degrades performance.