Knowledgebase: Using tape drives
Using the Tape Speed Test Utility
Posted by Sven Koester, Last modified by Sven Koester on 21 December 2017 15:45

As of 3.2.2, PresSTORE includes a simple tape drive speed test utility. This utility can be used to check the data transfer to and from a single tape drive.

In order to perform the test, please label a tape (preferably a new tape) in PresSTORE's Storage manager. When using a Jukebox / Media Changer, the tape must be transported to the drive as preparation for the test. Please use either the Jukebox' front panel menu or the Mount /Unmount Volume dialog in PresSTORE's Standalone Tape Drive Manager.

The utility performs read and write tests on the given tape drive,testing the data transfer speed to and from the storage sub system. 


Usage

The utility is exposed over the CLI interface like:

 cli::tests::tape::readwrite drivename datasize [blocksize]
 
The commands read/write data from/to the given PresSTORE drivename with the given  datasize using the optional blocksize.  (default = 32 kB).
Both sizes also accept the following optional modifiers:  
k|K = kilo (= size * 1024)                           
m|M = mega (= size * 1024 * 1024)                    
g|G = giga (= size * 1024 * 1024 * 1024)             
The command reports the write speed and the read speed, both in KBytes/sec.
For details calling commands via the CLI please consult the CLI guide.

Example:

# cd /usr/local/aw
  # bin/nsdchat -c cli::tests::tape::readwrite Drive1 1g
80659 74898 
# bin/nsdchat -c cli::tests::tape::readwrite Drive1 1g 64k
74898 74898
# bin/nsdchat -c cli::tests::tape::readwrite Drive1 1g 128k
80659 74898

The first command uses the default blocksize of 32 kB. Here (LTO3 device connected via Fibre Channel) the speed does not vary much with the blocksize, the results may differ when using other connection technologies, like SAS (Serial attached SCSI) for example. 

Note:
Not all blocksizes are supported, depending on the hardware. Namely on older SCSI devices, blocksizes above 32 KByte may be unsupported.
After performing the speed tests, the tape must be re-labeled in PresSTORE in order to be used again.

 
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