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Suggested BRU Block & Write Cache/Buffer Sizes and Timeout Settings for Tape Backups

Views: 18558
Votes: 10
Posted: 02 Oct, 2007

LTO , DLT , SDLT , SAIT , and VXA Drive and Library Configurations

Updated: May 14, 2009

BRU Server ships with default settings for the various drive operation timeout values (load, eject, & unload).  However, depending on the type of tape device that you are using, the default values may not be adequate.  Based on tests from the TOLIS Group Hardware Testing programs, we have found the following information for both required timeout and additional suggested buffer settings for LTO, DLT, SDLT, SAIT, and VXA drives and libraries that are running under BRU Server .

In the event that your timeout values are incorrect, the results can range from tapes not being properly unloaded in a library to tapes being improperly overwritten.  These situations are caused when a tape operation does not complete within the timeout assigned.  For overwritten tapes, this is caused when BRU Server does not recognize a previously used BRU tape because the tape does not come online before the online timeout expires.

Using the default buffer settings may simply result in less than optimal throughput on tape.

Please check your timeout and buffer settings and make changes as described below.  For instructions on where to find these settings, please refer to the BRU Server Admin Guide on the pages listed below.


LTO (All Versions):
  • Required Hardware Timeout Settings:
    • The following settings are assigned in the Console Preferences panel and are described on page 78 for the Mac Admin Guide and page 43 for the Linux Admin Guide.
      • SCSI Timeout: 1032
      • Online Timeout: 300
      • Eject Timeout: 1024
      • Needs Eject Timeout: 300
  • Additional Suggested Buffer Settings:
    • The following settings are assigned on the Console Device Configuration panel and are described on page 72 for the Mac Admin Guide and page 44 for the Linux Admin Guide.
      • Tape Block Size: 256Kb
      • Write Cache Size: 256MB
    Note: Please read TOLIS KB article #15 before making any changes to the tape block size.

DLT and SDLT (All Versions):
  • Required Hardware Timeout Settings:
    • The following settings are assigned in the Console Preferences panel and are described on page 78 for the Mac Admin Guide and page 43 for the Linux Admin Guide.
      • SCSI Timeout: 1032
      • Online Timeout: 300
      • Eject Timeout: 1024
      • Needs Eject Timeout: 300
  • Additional Suggested Buffer Settings:
    • The following settings are assigned on the Console Device Configuration panel and are described on page 72 for the Mac Admin Guide and page 44 for the Linux Admin Guide.
      • Tape Block Size: 256Kb
      • Write Cache Size: 256MB
    Note: Please read TOLIS KB article #15 before making any changes to the tape block size.

SAIT (not AIT 1, 2, 3, 4, or 5 drives):
  • Required Hardware Timeout Settings:
    • The following settings are assigned in the Console Preferences panel and are described on page 78 for the Mac Admin Guide and page 43 for the Linux Admin Guide.
      • SCSI Timeout: 1032
      • Online Timeout: 300
      • Eject Timeout: 1024
      • Needs Eject Timeout: 300
  • Additional Suggested Buffer Settings:
    • The following settings are assigned on the Console Device Configuration panel and are described on page 72 for the Mac Admin Guide and page 44 for the Linux Admin Guide.
      • Tape Block Size: 256Kb
      • Write Cache Size: 256MB
    Note: Please read TOLIS KB article #15 before making any changes to the tape block size.

VXA (All Versions with Latest Firmware):
  • Required Hardware Timeout Settings:
    • The following setting is required for all VXA libraries:
      • The "Needs Eject" check box must be checked under the Device Configuration options.  This allows for proper tape changes. The instructions for this can be found on page 72 of the Mac Admin Guide and page 44 of the Linux Admin Guide.
    • The following settings are assigned in the Console Preferences panel and are described on page 78 for the Mac Admin Guide and page 43 for the Linux Admin Guide.
      • SCSI Timeout: 1750
      • Online Timeout: 1273
      • Eject Timeout: 1273
      • Needs Eject Timeout: 1024
  • Additional Suggested Buffer Settings:
    • The following settings are assigned on the Console Device Configuration panel and are described on page 72 for the Mac Admin Guide and page 44 for the Linux Admin Guide.
      • Tape Block Size: 128Kb
      • Write Cache Size: 64MB
    Note: Please read TOLIS KB article #15 before making any changes to the tape block size.
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