Overview

Image copies

The BMC AMI Copy for Db2  (BMC AMI Copy) performs most of the functions of the IBM Db2 COPY utility and provides many other additional functions that the Db2 utility does not include.

Faster access methods and advanced features are used to implement a variety of backup strategies to support increasingly complex Db2 environments. Many of these additional backup strategies can significantly reduce the cost of ensuring that your table spaces and indexes can be recovered.

SYSCOPY maintenance

The SYSIBM.SYSCOPY table (often referred to as SYSCOPY) is the Db2 catalog table that tracks recovery information about spaces and partitions.

The main information that SYSCOPY contains is the registration of image copies. SYSCOPY also contains consistent points that are generated by the QUIESCE utility and marks utility events—such as reorganizations, loads, point-in-time recoveries, and terminated image copies—that affect the recoverability of a space or partition.

You may have to remove individual rows, register image copies, or modify copy information.

The BMC AMI Copy MODIFY command performs all of these tasks. The BMC AMI Copy MODIFY command also provides wildcard support and audit information. Additionally, the BMC AMI Copy MODIFY command synchronizes the integrated catalog facility (ICF) catalog and enhances performance.

Limitations of the IBM Db2 COPY and MODIFY utilities

Db2 offers the COPY utility to make image copies of table spaces and indexes with the COPY YES attribute and the RECOVER utility to restore an image copy and apply any changes made and logged since the image copy was made.

In most cases, if no full image copy is available, RECOVER cannot recover the data. For this reason, many Db2 users want to make multiple image copies available both on-site and at a remote recovery site.

If image copies are made infrequently, a large number of log records might need to be processed to recover the data. While log records are being processed, the data is unavailable and critical business applications might be inaccessible. Thus, it is necessary to make image copies often enough so that the data can be recovered in an acceptable amount of time. Indexes can also be rebuilt from the data. This process adds to recovery time.

If updates to the table space are allowed while an image copy is being made, the IBM Db2 COPY utility acquires and releases a lock for each page. This increases the cost of making the copy and might cause the IBM Db2 COPY utility to interfere with the performance of production jobs that are running. Also, image copies that are made while updates are allowed cannot be used for point-in-time recovery using the RECOVER TOCOPY option. For these reasons, many Db2 users choose to make their image copies during a time when production jobs are not running and choose not to allow updates while image copies are being made.

For SYSCOPY table maintenance, the MODIFY utility, which is a separate utility from the COPY utility available from IBM, gives you limited capabilities. You can remove rows entered prior to a user-specified date or rows that are older (in days) than a user-specified number of days. No other capabilities are available.

Benefits of BMC AMI Copy

By using advanced I/O techniques and providing additional functions, BMC AMI Copy can create image copies significantly faster than the IBM Db2 COPY utility and offers several significant benefits, as follows:

• Reduced costs due to:
  • Making image copies with fewer CPU cycles and EXCPs
  • Gathering RUNSTATS statistics and updating the Db2 catalog and the BMCSTATS table in the same pass as image copy creation
• Reduced elapsed time required to make image copies
• Improved recovery times due to:
  • Reduced copy costs and elapsed times encouraging more frequent copies; the more recent the image copy, the faster the recovery
  • The ability to back up indexes that are not defined as COPY YES or to back up nonpartitioned indexes by data set
  • The ability to make Instant Snapshot copies in conjunction with the BMC SNAPSHOT UPGRADE FEATURE (SUF) or EXTENDED BUFFER MANAGER (XBM) product for quick backup copies that can be restored using the BMC AMI Recover for Db2 and BMC AMI Recovery Manager for Db2 products
• Better control over the image copy process due to:
  • The multiple image copy capability
  • The merge copy capability
  • The conditional image copy capability--full, incremental, or none
  • Self optimizing I/O
  • Enhanced restart parameter options
  • Wildcard selection of spaces
  • Reduced JCL due to dynamic allocation of output copy data sets
  • Stacked tape output
  • Extended SHRLEVEL options, including the ability to copy groups of table spaces at the same consistent point while updates are in progress (using the BMC SUF or XBM product)
  • Grouping and multitasking for copies
  • Automatic stacked tape analysis by COPY IMAGECOPY to avoid excessive tape handling
  • Specification of how to handle error processing for unacceptable status or previously registered copies
  • The ability to specify how to handle migrated or archived spaces
  • The ability to allocate output differently for full or incremental copies
  • The ability to specify BMC AMI Recovery Manager object set as the source of the copy
  • The ability to specify application objects (such as those for SAP R/3 applications) by creator ID as the source of the copy
  • The ability to specify alternate dynamically allocated DDs or output descriptors with a threshold value for full copies to change the location or name of a full copy when the threshold value is met or exceeded (for example, the output for large image copies to go to tape rather than DASD)
  • The ability to compress disk copies with BMC Extended Compression Architecture (XCA) technology
  • The ability to use the XBM Utility Monitor available with BMC SNAPSHOT UPGRADE FEATURE (SUF) or EXTENDED BUFFER MANAGER (XBM) to view status information about your copy job as it is running
  • The ability to override some of the installation options for the current BMC AMI Copy execution
• Improved copy integrity by providing comprehensive Db2 page checking, including Db2 catalog hash and ring pointers
• Reduced time and resources by providing a means to perform enhanced SYSCOPY (and BMCXCOPY) maintenance and ICF catalog synchronization