Changing compression state

[Michel Looijs]

Hello,

First of all, sorry, I know for a fact this has been asked first, but digging through all the search hits was to timeconsuming.

I have an Ultrium-2 SCSI 448 tape drive, all the tapes are LTO2 tapes with 200/400 gigs. Now the problem is, 4 tapes DO have the 2:1 compression ratio, the tapes on which the differential backup is saved. However ALL my "Full" backup tapes have 1:1 compression, now i've tried to look everywhere but HOW canI change the compression rate for those tapes?

Im using Backup Exec 11d SP3, according to their support desk, its something you can adjust on either your streamer or your tapes.

Anyone with a helpfull insight would be fantastic I've been looking for 30 hours straight and still havent found a single option.

[Olibe Babaco · Accepted solution]

Hi Michael,

acc. to me forget about the the SW (BE 11d) compression), you better switch it from the HW.

By HP drives this goes through the LTT
Download yourself ver 4.6 from here

http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?pnameOID=406731&locale=en_US&taskId=135&prodSeriesId=406729&prodTypeId=12169

Check in user guide of LTT :

http://h18006.www1.hp.com/products/quickspecs/11591_div/11591_div.pdf

how to switch the compression:
By Win interface: this stand under utility.

To verify the compression for sure and check what you have done You can do a Support ticket or run compression test.

I hope this will help U

Regards

Olibe

p.s oh... yes if you have already turned on the BE compression, turn it of because they don't like each other much

here some further details for the compression (common info): http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=110&prodSeriesId=238671&prodTypeId=12169&objectID=lpg50244

[Michel Looijs]

Thank you for the reply, I was already in possesion of the L&TT Software and (thought) I looked throughout the software. I've found the Enable/Disable Compression option, but am uncertain of its usefullness.

I will take a deeper look into this and will try to do several test runs on the tapes that have given me the trouble so far.

Again, Thank you very much and I hope this will finally resolve the problem.

[Michel Looijs]

Well, i've been working on it for the entire week, but nothing seems to change.

The Compression is enabled in the Tape Tools, but the tapes that need to change from 1:1 to 2:1 refuse to be changed. For some reason I can load the tapes and have them scanned for information, but they just stay put at 1:1?!?!


After some time of trying trying and trying, the software suddenly showed me a compression rate of 1,73:1 for the Differential tapes and 1,44:1 for the Full tapes.

Who can help?!?!?!?

[Olibe Babaco]

HI Michel,

I just want to ask you whether this 1:1 still happens under switched-on SW (Backup Exec compression) + switched-on HW compression. I was unable to find this out in your post. If this is the case I will remind you what happens if you try for example zipping a jpeg -> bigger zip file, ok this happens with both compressions on.

I guess symantec can't say much more then this regarding the backup compression: http://seer.entsupport.symantec.com/docs/199542.htm

still i am wondering whether i already mentioned about the dev perf test.

Can you paste here some result with this test.
I dont know why but i guess you will get almost 40-4x MB/s -> if this appears to be so, then you have to consider start a thread by the symantec forum.

Just as a hint try some other SW to check whether this is only by BE 11d.
For example if you have something like NTbackup (some Win os, except the 2k8, for which i have no comment) specify HW compression and if it works fine- it's the backup exec,you have troubles with.


Here is an interesting link:
http://www.backupexecfaq.com/articles/problems/compression-is-turned-off.html

I have seen for first time, thanks to your post:)

I hope this helps you on your investigation

Best regards

[Michel Looijs]

Thank you again for responding in such a timely fashion.

We have fully disabled the SW compression in BE, although it didnt change a thing. I've erased all data on one of the tapes that was on 1:1, since they were not appendable because the media was full.

I'll try to do some test runs with that tape, but I hoped it would automatically switch to 2:1 when it was erased and reassigned.

Here is the outcome of a Drive Performance Test:
|__ Device Performance Test Started on Drive (Ultrium 2-SCSI) (Tape0)
|__ Testing with 2:1 Compression Ratio
|__ Opening Tape Drive Tape0
|__ Rewinding Tape
|__ Writing 1GB of 4GB
|__ Writing 2GB of 4GB
|__ Writing 3GB of 4GB
|__ Writing 4GB of 4GB
|__ 4 GB written in 188 seconds at 21 MB/s
|__ Rewinding Tape
|__ Closing Tape Drive Tape0


This unfortunatly is performed on a tape that DOES have 2:1 compression. Ill be able to test more on Friday.

I hope this helps a bit more.

Thanks in advance.

Kind regards,
Michel Looijs

[Olibe Babaco]

Hi Michel,

is this drive still under warranty. If it is, i will suggest you contact the hp guys and ask for replacement, i guess you have done more then the needful to prove the drive is not working properly.


Regards