Setting options to minimize processor usage

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You can set several client options to reduce the time that is required for client processing tasks and improve performance. The client options to consider are quiet, virtualnodename, ifnewer, incrbydate, and tapeprompt.

For Mac OS X file systems, limiting the length of extended attributes can help improve the client performance.

For clients on any operating system, turning off antivirus programs, or other programs that compete with the client for system resources, can also improve client performance.

quiet client option

Two client options determine whether messages are displayed during backup operations: quiet and verbose. The verbose client option is the default option; it causes messages to be displayed in the output during client operations. The quiet client option can be set to suppress messages from being displayed.

When you set the quiet option, messages and summary information are still written to the log files, but they are not displayed in GUI or command-line output. The quiet option provides two main benefits that can improve client performance:

  • For tape backups, the first transaction group of data is always resent. To avoid the transaction from being resent, use the quiet option to reduce retransmissions at the client.
  • If you are using the client scheduler to schedule backups, the quiet option reduces entries in the schedule log, which might improve client throughput.

Although the quiet option can offer some modest performance improvements, consider using the default (verbose) option. The benefits of having messages displayed and logged can outweigh the performance gains that the quiet option provides.

virtualnodename client option

When you restore, retrieve, or query objects that are owned by another node, consider using the client virtualnodename option instead of the fromnode option.

The fromnode option uses more system resources than the virtualnodename option. By using the virtualnodename option instead of the fromnode option, you might improve client performance.

ifnewer client option

The ifnewer client option is used only with restore commands. This option can reduce network traffic during restore operations. This option ensures that files are restored only if the date of the file that is stored on the server is newer than the date of the same file that is stored on the client node.

The ifnewer option can be set only on the command line, and, like all options that are specified on the command line, it must be preceded by a hyphen (-) character. For example:
dsmc restore "/home/grover/*" -sub=y -rep=y -ifnewer

incrbydate client option

The incrbydate client option can shorten backup windows because the option causes the client to back up objects only if they are new, or changed, since the last incremental backup was run. As its name implies, this option can be used only to perform incremental backups.

Incremental backups that use the incrbydate option, have limitations that regular incremental backups do not have. You must understand these limitations to correctly use this option. For incremental by date backups, consider the following limitations:
  • Files that are created or modified after a directory was processed by the IBM Storage Protect client, but before the backup completes, are skipped at the next incrbydate backup.
  • incrbydate backups do not cause expired files to be deleted from the server.
  • If a management class changes for a file or a directory after an incrbydate is run, the stored objects are not rebound to the new management class.
  • After an incrbydate backup runs, if only the attributes of an object are changed, the file is not included in the next incrbydate backup.

During an incremental backup operation, where the incrbydate option is not used, the server reads the attributes of all the client files that are in the server file system and passes this information to the client. The client then compares the server attribute list to all of the files in the client file system. This comparison can be time-consuming, especially on clients that have limited memory.

With an incremental-by-date backup, the server passes only the date of the last successful incremental backup operation to the client and the client backs up only files that are new or changed since the previous incremental backup. The time savings can be significant. However, regular, periodic incremental backups are still needed to back up files workstation files that are excluded from backups, by the limitations of incremental by date backups.

For example, if a new file in your file system has a creation date that is earlier than the last successful backup date, future incremental-by-date backups do not back up this file because the client assumes that the file has already been backed up. Also, files that were deleted are not detected by an incremental-by-date backup and these deleted files are restored if you perform a full system restore.

For a full list of restrictions about the incrbydate option, see incrbydate option.

The incrbydate option can be specified only on the command line with the incremental command. Like all options that are specified on the command line, it must be preceded by a hyphen (-) character. For example:
dsmc incremental -incrbydate

Consider journal-based backups as an alternative to incremental by date backups. Journal-based backups perform a traditional incremental backup of the file system when the first backup occurs. A journal file records which file system objects are changed after the initial backup, and the journal is used to determine which objects to include in subsequent backups. Journal-based backup is most appropriate for file systems that do not change many objects, often. For more information about journal-based backups, see Journal-based backupJournal-based backup.

tapeprompt client option

The tapeprompt client option specifies whether you want to be prompted to wait for a tape to be mounted, if a tape is required to back up or restore objects.

Backup and restore, and archive and retrieve operations can be processed with fewer interactive input delays if you specify tapeprompt no. With tapeprompt no specified, the client still waits for tapes to be mounted if they are required, but the prompts that ask whether you want to wait for a tape, or skip objects that require a tape, are suppressed.