Ultrium 215: I'm not sure the hardware compression is working

[Wingene]

Hi

I'm using a HP Storage Works Ultrium 215 with HP LTO-tapes (C7971A) to backup. This tapes have a raw capacity of 100 GB and are able to backup up 200 GB when using a compressionratio 2:1 (that's pretty logic hein).

I'm using Symantec Backup Exec 11d.
I'm not sure this compression is working well.

When I use HP Storageworks Library & Tape Tools; I get this info. It says "L&TT determined that your hardware compression algorithm is switched off"  How can you switch this on?

"|__ Analysis Results
    ||__ Compression test started
    ||__ Testing the Ultrium 1-SCSI
    ||__ Before running this test, L&TT determined that your hardware compression algorithm is switched off.
    ||__ This was probably set by your backup software or by other software utility.
    ||__ L&TT will enable the drive hardware compression for the test.
    ||__ On completion, it will revert the drive setting.
    ||__ Compressed write transfer rate = 13.48 Mb/sec (I/O path, not backup data rate)
    ||__ Compressed read transfer rate = 14.63 Mb/sec (I/O path, not backup data rate)
    ||__ Read compression ratio is: 2.62 : 1
    ||__ Write compression ratio is: 2.62 : 1
    ||__ Total MB sent to host: 1199"

But I doubt the compression algorithm is realy switched off

In symantec backup exec, I'm seeing things that indicate that more then 100 GB is backed up.

When I look to the statistics of a media I see
that 132 GB of data has been backed up, but the compressratio is 1:1.
A bit weird for tapes that have a raw capacitiy of 100 GB

Any ideas what is wrong?

I'm working on this because alerts indicate that BE is asking for a new tape during the night.  So there is not enough space on the tape.

(configured options in backup exec:

In the device properties => tab 'configuration', hardware compression is enabled and I'm using the default settings.
In the job properties hardware compression is enabled (Hardware [if available, otherwise none])

)

Best regards

Tom

[Wingene]

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50030

says

"With some of our DAT tape drives, the configuration switches can override the software control of the hardware compression."

I don't what is meant by the configuration switches.  Should that be a switch (jumper?) on the device?

[Wingene]

The default settings in backup exec for the hardware compression on the device are:

blok size (per device): 64 K

buffer size (per device): 64 K

Buffer count: 0

High water count: 0