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October 12, 2010

DB2 and IMS Data Sharing Data Corruption

IBM just released an alert regarding potential data corruption for IMS and DB2 for z/OS following rebuild of lock structures in data sharing mode.

According to IBM, "during rebuild of a lock structure in a DB2 V8 or DB2 V9 data sharing environment, two problems may occur when locks are being rebuilt asynchronously into the new structure:

1.    The IRLM may incorrectly conclude that the rebuild is complete before all locks have been rebuilt into the new lock structure. This can cause new lock requests to be granted prematurely, resulting in incompatible locks being held across the data sharing group.
2.    The IRLM may ABEND before all locks have been rebuilt. In this case, locks that were not rebuilt in time will be lost and will not be reacquired on restart."

Since the problem is in IRLM, all versions of IMS may also be affected.

IBM recommends that users install APAR PM23662. Users should also, if possible, avoid rebuild of IRLM lock structures until this APAR is applied to all members of the data sharing group. Further information is available here.

As I've noted before, the IBM Red Alert suscription service is a useful tool for IT professionals who maintain zSeries servers. To receive notifications of Red Alerts, register here.