Adjusting the I/O buffer size of the client

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The diskbuffsize client option specifies the maximum disk input/output (I/O) buffer size (in KB) that the client uses when it is reading files.

Optimal client performance during backup, archive, or HSM migration processes might be achieved if the value for this option is equal to or smaller than the amount of file read ahead that is provided by the client file system. A larger buffer requires more memory and might not improve performance.

The default value is 32 KB for all clients except clients that run on AIX®. For clients that run on AIX operating systems, the default value is 256 KB, except when enablelanfree yes is specified. When enablelanfree yes is specified on AIX, the default value is 32 KB. API client applications have a default value of 1023 KB, except for Windows API client applications, version 5.3.7 and later, which have a default value of 32 KB.

The default value is the preferred value for the client operating system.

If the performance of restore operations seems slow, consider resizing the diskbuffsize option:
  1. Stop the current restore operation.
  2. Set this option in the appropriate server stanza in the dsm.sys file: diskbuffsize 32.
  3. Restart the restore operation.