Wednesday, August 1, 2012

Vacation: Time to REBALANCE (and to look at DB2 10)

It is vacation time, time to recharge and to rebalance life (BTW: Some years back some companies talked about work-life balance, now it is "work/life integration" - towards always on). When I thought about "rebalance", some new DB2 features came to mind. You see, I am still in work mode...

When changing storage in DB2, e.g., adding containers to a tablespace or removing them from it, the tablespace is rebalanced to keep it evenly striped. DB2 10 introduced the concept of storage groups. It allows to group tablespaces with similar properties or "tasks" together. Using ALTER TABLESPACE it is possible to change the associated storage group. To move the data from the former to the new storage (group), data is rebalanced in the background, i.e., asynchronously. To have greater control over those background tasks, DB2 10 adds SUSPEND and RESUME to the ALTER TABLEPACE ... REBALANCE statements. So you can decide when to take a break...

As you might know, there is another rebalance operation available in DB2, storage-related again. It is used in pureScale environments after changes to the shared file system (cluster file system) and rebalances storage utilization. The rebalance option is part of the db2cluster command which is used to interact with the reliable, scalable cluster infrastructure (RSCT) and the cluster file system GPFS.

As both rebalance operations are recommended for "periods of low system activity", this could mean vacation time - bringing me back to what I am preparing for...

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