Does HP C7369-20906 LTO support hardware compression

[Dick Starr]

My Dell Powervault 110T LTO (HP C7369-20906) will not compress data even though "Enable compression" is clicked in "Devices - Properties - Configuration" and the backup job has compression type "hardware, if available, otherwise none". The tape drive is installed in a Dell 6600 server running Windows 2003 server and Backup Exec 12.5.

There is compressible data on this server. I have tried the backup job setting "hardware, if available, otherwise software".

[TTr · Accepted solution]

Most likely hardware compression is always on and you should leave your backup exec setting to "hardware, if available, otherwise none".
Measure how much data you have written in a single tape. If it is much more than 100GB then compression is on.

[Dick Starr]

Thanks for the reply. If I right-click the tape on the Media Set tab it shows the tape with just a few MB less than 100GB and no compression; Backup Exec then asks for a second tape.

One interesting thing is that the Job Monitor byte count is is about 50GB when it asks for a second tape. If I put in a second tape it writes about another 6GB with the Job Monitor byte count showing about 56GB when the job completes. My backup job always overwrites the tape, so it is not appending. When I format a tape the Media Set tab shows 100GB available on that tape.

[TTr]

Verify that the "inquiry string" in backup exec is correct. See ftp://exftpp.symantec.com/pub/support/products/Backup_Exec_for_WindowsNT/306831.pdf

It looks like the drive has hardware compression but is it possible that Dell disables it in the PowerVault 110T? There is no mention of compression in the PowerVault 110T in this page by Dell (this is for LTO2 and LTO3 I could not find any for LTO1). http://www.dell.com/downloads/global/products/pvaul/en/pv110tlto_spec.pdf

Are there any switches on the drive that may enable/disable compression? You may have to open it up to check.

Have you tried using any other utilities to write to the drive to see how much data you can fit in it?

Download and use the LTT (Library and Tape Tools) to check what is reported by the drive. Check if you need newer drivers too.
http://dell.driversdown.com/dell-drivers-list/s_84_1.shtml

The LTT is originally from HP http://h18000.www1.hp.com/products/storageworks/ltt/index.html

[Dick Starr]

Thanks again. I now know the drive supports compression but Backup Exec turns it off.

I had previously downloaded "Dell Library & Tape Tools" but it didn't do much; I did use it to update the firmware to "E31E". After downloading & installing "HP Library & Tape Tools version 4.10" last night I realized that the Dell version was just a Dell named early version of the HP program.

Version 4.10 has a compression test and also can set compression on the drive. I ran the compression test: it told me compression was off but it would turn it on for the test; test passed. I used their utility to turn compression on. After rerunning the compression test to verify compression was on I did a Backup Exec test; no compression. I reran the compression test and it said compression was off.

I will work on it again this evening and report back to this thread.