Tape Drive Testing and Optimization

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SANtools software is uniquely qualified to empower you to diagnose and treat tape performance and reliability issues you probably didn't even know you have.  This section shows a subset if information taken from a tandberg tape drive using our software and covers some things that administrators should consider when maintaining tapes. The information below is taken from other pages in the documentation, and summarized below for your convenience.

 

Firmware Updates

You should always check to insure you have current firmware.  Enter smartmon-ux -I+ to report details about your tape subsystem that will make it easy for you to determine what firmware you are running (and often how old it is).  For this particular model of tape, we are also able to report that the firmware was written on 07/02/2003, and the tape drive was manufactured back in 2001.  It has never had a factory adjustment.

 

Vendor Identification:               TANDBERG

Product Identification:              SLR7

Firmware Revision:                   0595

Drive manufacturing MM.DD.YY:        06.12.01

Main microcode creation MM.DD.YY:    07.02.03

DSP microcode creation MM.DD.YY:     07.02.03

Last drive adjustment MM.DD.YY:      ........

 

If your firmware is old, and you are lucky, then your manufacturer has a program that you can run to upgrade the firmware.  99% of the time, the program is written exclusively for Windows.  Our tandberg was attached to our in-house Sun, and Tandberg does not distribute a program that lets you upgrade firmware under anything but 32-bit windows.   The firmware that this tape is now running, version 595, was upgraded on our sun by entering smartmon-ux -flash S07d0595.bin. (Release 1.42 removed the artificial constraint that limited firmware flashing to SCSI/SAS/FC disk drives and SES enclosures.  You can now flash any peripheral that uses the SCSI protocol.  Keep in mind, however, that manufacturers sometimes add a "wrapper" to firmware files that requires you to flash using the manufacturer's utility.  You should always contact your manufacturer before flashing firmware upgrades.  We will be happy to work with them to qualify our software for firmware updates .. especially if the manufacturer can not help you with non-windows hosts.

 

Compression Efficiency

Hardware or software compression, which is best?  How do you tell if hardware compression is enabled on the tape drive?  (See the DCE setting)  The answer is that it depends.  Our software will provide you the tools you need to measure true compression, compare different algorithms (if your tape is equipped), and see if your tape operates more efficiently using one method or another.   The information below comes from viewing the log pages after a backup run. Further down, you will see some configurable mode pages parameters and settings.

 

Just run smartmon-ux -Cx before and after a test run, and use the results to establish effectiveness of your settings down to the exact byte count.

 

 Total logical data blocks transferred: 7248

 Total physical blocks written to media: 55023104

 Total physical blocks read from media (Read and Space operations only): 101376

 Write compression ratio (percentage - reset on cartridge change): 168

 Read compression ratio (percentage - reset on cartridge change): 0

 Percentage of data with compression between .89 and 1.2 - reset on cartridge change: 0

 Percentage of data with compression between 1.2 and 1.6 - reset on cartridge change: 28

 Percentage of data with compression between 1.6 and 2.2 - reset on cartridge change: 71

 Percentage of data with compression between 2.2 and 3.6 - reset on cartridge change: 0

 Percentage of data with compression greater than 3.6 - reset on cartridge change: 0

 Bytes processed (on Writes): 295436288

 Unrecovered errors (on Writes): 0

 Bytes processed (on Reads): 7602176

 

Tape Drive Configurable Mode Page Parameters

Our tandberg isn't very configurable (the R/O means the field is read-only), but other manufacturers provide much greater room for tweaking settings.  If you read the full manuals for the most popular software, you will find that they usually provide "best practice" settings.  You will be amazed at how much your performance may improve if your buffer size is too small or too large, as an example.

 

Read-Write Error Recovery                : Page [01h] (Factory, Current, Saved)

Transfer block (TB)                     : 0, 0, 0 {R/O}

Enable early recovery (EER)             : 1, 1, 1 {R/O}

Post error (PER)                        : 0, 0, 0 {R/O}

Disable transfer on error (DTE)         : 0, 0, 0 {R/O}

  Disable correction (DCR)                : 0, 0, 0

  Read retry count (RRC)                  : 24, 24, 24

  Write Retry Count (WRC)                 : 16, 16, 16

 

Disconnect-Reconnect                     : Page [02h] (Factory, Current, Saved)

  Buffer full ratio (BFR)                 : 16, 16, 16

  Buffer empty ratio (BER)                : 16, 16, 16

Bus inactivity limit (BIL)              : 0, 0, 0 {R/O}

Disconnect time limit (DTL)             : 0, 0, 0 {R/O}

Connect time limit (CTL)                : 0, 0, 0 {R/O}

  Maximum burst size (MBS)                : 0, 0, 0

Enable modify data pointers (EMDP)      : 0, 0, 0 {R/O}

Fair arbitration (FA)                   : 0, 0, 0 {R/O}

Disconnect immediate (DImm)             : 0, 0, 0 {R/O}

Data transfer disconnect control (DTDC) : 0, 0, 0 {R/O}

First burst size (FBS)                  : 0, 0, 0 {R/O}

 

Data Compression                         : Page [0Fh] (Factory, Current, Saved)

DCE                                     : 1, 0, 1

DCC                                     : 1, 1, 1 {R/O}

DDE                                     : 1, 1, 1

RED                                     : 0, 0, 0

Compression algorithm                   : 00000003h, 00000003h, 00000003h

Decompression algorithm                 : 00000000h, 00000003h, 00000000h

 

Tape Control                             : Page [10h] (Factory, Current, Saved)

Change active partition (CAP)           : 0, 0, 0

Change active format (CAF)              : 0, 0, 0 {R/O}

Active format                           : 0, 0, 0 {R/O}

Active partition                        : 0, 0, 0

Write buffer full ratio                 : 0, 0, 0 {R/O}

Read buffer empty ratio                 : 0, 0, 0 {R/O}

  Write delay time (in 100ms)             : 0, 0, 0

Data buffer recovery (DBR)              : 0, 0, 0 {R/O}

Block identifiers supported (BIS)       : 1, 1, 1 {R/O}

Report setmarks (RSMK)                  : 1, 1, 1 {R/O}

Automatic velocity control (AVC)        : 0, 1, 1

Stop on consecutive filemarks (SOCF)    : 0, 0, 0 {R/O}

Recover buffer over (RBO)               : 0, 0, 0 {R/O}

Recover error warning (REW)             : 0, 0, 0 {R/O}

Gap size                                : 0, 0, 0 {R/O}

EOD Defined                             : 0, 0, 0 {R/O}

Enable EOD generation (EEG)             : 1, 1, 1 {R/O}

Synchronize early warning (SEW)         : 1, 1, 1 {R/O}

Soft write protect (SWP)                : 0, 0, 0 {R/O}

Buffer size at early warning            : 000000h, 000000h, 000000h

Data compression algorithm              : 00h, 00h, 00h

Associated write protect (ASOCWP)       : 0, 0, 0 {R/O}

Persistent write protect (PERSWP)       : 0, 0, 0 {R/O}

Permanent write protect (PRMWP)         : 0, 0, 0 {R/O}

 

Is tape drive starting/stopping too often or slow?

Look at the disconnect-reconnect settings and some of the highlighted fields above. Both your tape backup software vendor and hardware vendor should have good information on what settings are "best".  The built in mode-page editor can be used to set these to optimal values. Often you just need to modify something like a buffer empty or buffer full ratio setting.

 

Is performance suffering due to media problems and/or errors?

Below comes from the log page inquiry.  (By the way, you can monitor these values real-time during a backup via threshold monitoring. Any error, whether corrected or uncorrected will require everything to stop for retries and data correction attempts.

 

Note that our software does not keep track of how many times a tape has been used, or cleaned, or if the heads are dirty.  Most tape drives have this built-in capability, and our software provides this information to you.

 

 Number of minutes of motion since last head cleaning: 94

 Number of head cleanings: 5

 Number of lost servo locks on writes: 0

 Number of write servo dropouts: 0

 Number of lost servo locks on reads: 0

 Number of read servo dropouts: 0

 Cartridge serial number: 496256  

 Number of times this cartridge loaded: 18

 Number of beginning-of-tape markers passed for this tape: 253

 Number of end-of-tape markers passed for this tape: 14

 Number of cartridge write past counters: 27

 Number of minutes cartridge has been in motion: 121

 Buffer under-runs: 22

 Buffer over-runs: 1

 Write errors corrected with possible delays: 155808

 Total Write errors: 345

 Write errors corrected: 345

 Times correction algorithm processed (on Writes): 0

 Bytes processed (on Writes): 295436288

 Unrecovered errors (on Writes): 0

 Read errors corrected with possible delays: 0

 Total Read errors: 1

 Read errors corrected: 1

 Times correction algorithm processed (on Reads): 1

 Bytes processed (on Reads): 7602176

 Unrecovered errors (on Reads): 0