Limited supportBMC provides limited support for this version of the product. As a result, BMC no longer accepts comments in this space. If you encounter problems with the product version or the space, contact BMC Support.BMC recommends upgrading to the latest version of the product. To see documentation for that version, see BMC AMI Copy for Db2 13.1.

Specifying conditional image copies

BMC AMI Copy

 provides options on the COPY command that conditionally make an incremental image copy, a full image copy, or no copy.

The type of copy made is dependent on user-defined thresholds.

The FULL AUTO FULLPCT option and the CHANGELIMIT option are effectively the same and act on two values, incrPct and fullPct, to determine what type of copy to make. incrPct and fullPct are positional parameters. If you use a comma in the expression and do not specify incrPct, incrPct defaults to the installation option INCRPCT. If you use a comma and do not specify fullPct, fullPct defaults to the value of the installation option FULLPCT. The default value of the INCRPCT installation option is zero (0). The default value of the FULLPCT installation option is 50. The values for the installation options INCRPCT and FULLPCT must be integers. However, when you set incrPct and fullPct using FULL AUTO FULLPCT and CHANGELIMIT, integer or decimal values are valid.

FULL AUTO FULLPCT (fullPct) or CHANGELIMIT (fullPct) is equivalent to (0, fullPct), which makes either an incremental copy or a full copy—an incremental copy if the percent of changed pages is less than fullPct, or a full copy if greater than or equal to fullPct.

You can also specify the value of incrPct and fullPct as the keyword, ANY. You can use ANY to create an incremental or full copy if any pages are changed, instead of based on whether the percentage of changed pages falls within the specified range of values. 

You can specify incrPct as the keyword, ANY in the option statement, CHANGELIMIT (incrPct, fullPct). If you use CHANGELIMIT (ANY, fullPct), BMC AMI Copy creates an incremental copy if any pages are changed, and the percentage of pages changed does not exceed the value of fullPct. If the percentage of pages changed equals or exceeds the value of fullPct, BMC AMI Copy creates a full copy. 

You can specify fullPct as the keyword, ANY in the option statement, CHANGELIMIT ( fullPct). CHANGELIMIT ANY creates a full copy if any pages are changed.

Important

 You cannot use ANY with the FULL AUTO option.

To bypass a copy for a space with no changed pages, specify FULL AUTO FULLPCT (0, fullPct) or CHANGELIMIT (0, fullPct). In this case, BMC AMI Copy makes an incremental copy if any pages have changed or a full copy if the percentage of changed pages exceeds fullPct. However, an exception occurs when you specify incrPct as 0 and EMPTY NO, in which case BMC AMI Copy makes a copy even if there are no changed pages if BMC AMI Copy is able to acquire a registration point.

Important

You cannot use CHANGELIMIT, FULL AUTO FULLPCT, FULLPCT, or INCRPCT for a table space or partition defined with TRACKMOD NO. If you change the TRACKMOD option from NO to YES, you must take a full image copy before you can use these options. BMC AMI Copy forces FULL YES escalation when any ALTER is detected. (FULL AUTO is allowed, but only with MAXINCRS and FULLDAY for determining whether the copy is full or incremental).

FULL AUTO FULLPCT (incrPct, fullPct) or CHANGELIMIT (incrPct, fullPct) are evaluated as follows:

  • If the percent of changed pages is less than or equal to incrPct (x <= incrPct), do not make a copy.
  • If the percent of changed pages is greater than incrPct but less than fullPct (incrPct < x < fullPct), make an incremental copy.
    If the value of incrPct is specified as ANY (i.e. option statement CHANGELIMIT (ANY, fullPct) is used), make an incremental copy if any pages are changed, but the percentage of pages changed does not exceed fullPct.
  • If the percent of changed pages is greater than or equal to fullPct (x >= fullPct), make a full copy.
    If the value of incrPct is specified as ANY (i.e. option statement CHANGELIMIT (ANY, fullPct) is used), make a full copy if any pages are changed, and the percentage of pages changed exceeds fullPct.

FULL AUTO FULLPCT (incrPct,0) or CHANGELIMIT (incrPct,0) allows you the flexibility to make an incremental copy or no copy at all. If the percent of changed pages is greater than incrPct, an incremental copy will be made. Otherwise, no copy will be made. The 0 in fullPct prevents escalation to a full copy based on changed pages although it might escalate for other reasons.

Remember the following things when making conditional copies:

  • BMC AMI Copy uses RTS to calculate changed pages and estimate the size of an incremental copy.
  • If the (incrPct, fullPct) format is used, it is possible that BMC AMI Copy will not make an image copy at all. Therefore, BMC AMI Copy will determine the percent of changed pages before QUIESCE processing to avoid dynamic allocation of the output data set. If the (fullPct) format is used, the estimate will occur after QUIESCE processing.
  • If FULL AUTO FULLPCT (fullPct) is specified and there are no changed pages, an incremental copy will be registered only if you specified the FULL AUTO EMPTY NO option and BMC AMI Copy is able to acquire a registration point.
  • The parentheses around incrPct and fullPct are optional and are shown in the text above for clarity.

If you specify both FULL and CHANGELIMIT, the option specified last will be used, the copy will continue, and a warning is issued as shown in the following example:

COPY TABLESPACE ACPDB40.TS40N1
     DSNUM ALL
     FULL YES CHANGELIMIT 10,20

The following message is issued and the run ends with RC=4:

BMC30119W OPTION CHANGELIMIT IS A DUPLICATE AND ITS VALUE REPLACES THE PREVIOUS VALUE

For multi-data-set, nonpartitioned spaces, if you specify FULL AUTO or CHANGELIMIT with DSNUM DATASET, be aware of the following behavior:

  • Changes for all data sets are considered when computing the percent changed (as would occur if you specified DSNUM ALL).
  • All data sets are forced to the same ICTYPE (such as full or incremental) and they are also handled by the same output descriptor.

  • (SPE2010) The OUTSIZE comparison, which determines which output descriptor should be used, uses the total number of pages of all data sets including the total number of pages or the estimated total changed pages.

For more information about the syntax descriptions for the FULL AUTO FULLPCT and CHANGELIMIT options, see Global-COPY-options.

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