Important We are integrating BMC AMI LOBMaster technology into the BMC AMI Reorg product and discontinuing BMC AMI LOBMaster as a separate product. For the latest integrated documentation, see BMC AMI Reorg for Db2 13.1.

Benefits of BMC AMI LOBMaster

BMC AMI LOBMaster is the BMC solution for reorganizing LOB data.

LOBs are an essential tool in database design, but they can be extremely large. For each LOB column, each partition of a table space can have an associated LOB table space of up to 128 TB with 4096 base table space partitions. The sequential read and write of a 200-GB LOB (small compared to the potential maximum size) can take three to four hours, ignoring any data processing. Therefore, one of the biggest challenges of big data is the need to reduce the processing time of LOBs.

In Db2, owing to the size and structure of LOBs, you need to run multiple Db2 utilities to perform maintenance tasks (for example, to perform a validity check or reorganize table spaces that have LOB columns). BMC AMI LOBMaster enables you to perform these tasks significantly faster.

Related topics

Getting-started-with-BMC-AMI-LOBMaster

Large-object-LOB-components 

BMC-AMI-LOBMaster-command-and-syntax-reference

Reporting-for-BMC-AMI-LOBMaster

Running-BMC-AMI-LOBMaster

BMC AMI LOBMaster provides benefits in terms of ease of use and improved performance.

Ease of use

In Db2, to check the validity of the base table space, LOB index, and LOB table space, you need to run the following utilities:

  • CHECK INDEX
  • CHECK LOB
  • CHECK DATA
  • REPAIR

BMC AMI LOBMaster automatically performs validity checking without running these utilities. When reorganizing LOB data, BMC AMI LOBMaster provides this functionality by enabling you to add the AUX keyword to the REORG statement for the base table space. This keyword tells the utility to reorganize the LOB auxiliary table spaces concurrently with the base table space. You do not need to identify which table spaces have LOBs defined; the AUX keyword is ignored for table spaces that do not contain LOBs. This capability simplifies and speeds up the management of objects with LOB columns.

BMC AMI LOBMaster discards or unloads all LOBs for a base table space row in a format that is suitable for a load utility and dynamically allocates the unload file. (You must include the XULDDYNM automation control point to enable BMC AMI LOBMaster to dynamically allocate your unload file.)

Performance

BMC AMI LOBMaster uses the following sophisticated techniques to enhance the performance of LOB reorganization:

  • BMC AMI LOBMaster uses parallel I/O tasks to read LOB table spaces. BMC AMI LOBMaster can use up to eight different tasks, depending on the size of the LOB.
  • BMC AMI LOBMaster performs read tasks with sequential rather than random I/O. Sequential I/O is significantly faster. With eight parallel read tasks running, net I/O speeds can exceed 600 cylinders per second, or about 5 seconds per gigabyte. Reading a 200-GB LOB takes significantly less than 20 minutes.
  • BMC AMI LOBMaster analyzes the integrity of the LOB data without invoking an external sort routine.
  • BMC AMI LOBMaster uses parallel subtasks to write the output LOB table space. By using a separate subtask per output data set (not table space), BMC AMI LOBMaster can schedule up to 254 tasks. (The number of tasks that can run in parallel, however, is limited to eight.)
  • All partitions run independently and use the unique BMC AMI Utilities primary-server technology. Each partition can be run simultaneously on different CPUs in different jobs, even on different members of a sysplex.

Conditions that require BMC AMI LOBMaster

To ensure that your base table space and its associated LOB table spaces remain synchronized, you must use BMC AMI LOBMaster and specify the AUX keyword on the REORG command when either of the following conditions exist:

  • You are reorganizing a table space that contains a LOB column and you are discarding rows during the reorganization.
  • You are reorganizing a partition-by-growth (PBG) table space that contains a LOB column.

 

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