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Database Administrator's Guide

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Backup as Multiple Extent Files

The Dynamic Dump backup feature defaults to breaking-up the backup file (stream file) into multiple physical files (segments). This gets around individual file size limits imposed by the host OS (e.g., 2GB for a typical Unix system). Each backup file segment defaults to 1GB. There is no limit on the number of backup files (segments) supported.

Use the !EXT_SIZE keyword to change the segment size at runtime (up to 2000MB) by setting the argument of !EXT_SIZE to the desired number of bytes. Set the argument to NO to disable this feature and limit the dump to one file up to the OS maximum file size.

When a backup stream file is broken into segments, they are named as follows: original.001, original.002, etc, unless the original dump file has a name of the form name.nnn where nnn represent digits. For example, if the original dump file is named dump.str, the first additional segment after dump.str gets to the extent size will be dump.str.001. However, if the original dump file is named dump.111, then the first extent will be dump.112.

On some systems, the dynamic dump extent names formed from the original dump stream file name by adding .001, .002, etc. are not legal. Therefore, the extent name is first checked internally. If it does not work, the original dump stream file name is modified to produce a safe name in one of the following ways:

  • Replace name extension, if any, in original with numeric name extensions (.001, .002, etc.).
  • If the original name had no name extension, truncate the name to 8 bytes, and add numeric name extensions.
  • If the original name had no name extensions and is not more than 8 bytes, use the name FCSDDEXT.001 for the first dump stream segment, incrementing the numeric name extension as needed.