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Compression enabled but not working BE 12.5 + DAT72 170M 36/72GB tapes

Whitmore29
Level 3
Hi all,

This is my first post on this forum ... yay!, However it is pain and hardship that has brought me here. Our BE is setup to "Hardware Compression else none" for full and diff jobs, xtalk utility reports that compression on the drive (Dell PV-100T-Dat72) is enabled the drive does however recignize the DAT72 tapes correctly (heard this was an issue perhaps in previous versions?). However jobs still finish at a compression ratio of 1:1 with not a singly byte in the byte count different between before and after. When i run NTbackup however just for comparisons sake compression does work. Not sure at the exact ratios i just chose files that were larger than 36GB and ran it to verify that it wasn't a hardware issue. so that leads me back to BE as the issue... however i am a fairly new user with the system so it is entirely possible that there is a mistake in my configuration somewhere. thats where you come in... any ideas what i can look at to find my underlying issues?

Thanks so much in advance this has been driving me nuts now for about 2 weeks! 

Oh BTW I have tried every driver under the sun for this tape drive and all yield the same results as well i am using the most up to date firmware that dell has to offer for my drive...


Thanks again!

Chris

24 REPLIES 24

Ben_L_
Level 6
Employee
Give this technote a shot to verify compression is working.

http://seer.entsupport.symantec.com/docs/287662.htm

Whitmore29
Level 3
thanks for the quick reply!

ATM BE is running the job from last night beacuse it ran over into the second tape so after that is done i will give this a shot...

Whitmore29
Level 3
I followed the steps on the page provided and indeed it is turning compression off. even though set to on. Like i mentioned before compression works flawlessly in NTbackup so i guess this just narrowed it to being a BE problem or config error... where should i look next ?

Thanks for the help so far!

Note: if it matters the 7th bit of the data was a 40 not 00 i don't know if that gives any more information however it is showing as the 40 in both the sence and the select operations.

Ben_L_
Level 6
Employee
Can you post the bin file from tracer so that I can take a look at it?

Ben_L_
Level 6
Employee
Can you attach the bin file so that I can download the file and review it?

Whitmore29
Level 3
I'll have to get a new one i just exported the text file from it give me a few...

Whitmore29
Level 3
not sure if there is a native way to upload a file to this site but either way you cna get it from here...

http://www.mediafire.com/?sharekey=5ec8287a9a82b6dcc79b87b207592a1ce04e75f6e8ebb871

edit: is it just me or does this file appear to have compression on ... ? either way the ratio reported on the tape is 1:1

Whitmore29
Level 3
edit: removed the text so the thread stays clean ...

Ben_L_
Level 6
Employee
That trace does show compression getting enabled.  That tells me that BE is sending the correct commands to the tape drive to enable compression. 

I would suggest making sure you have the latest firmware for the drive, latest SCSI drivers for the SCSI card.  If compression is still not working after that and the trace shows compression turned on, you will need to get in touch with the hardware vendor.  All BE does is send the commands to the drive to enable/disable compression, if compression is getting enabled (like the trace shows) then something is wrong on the hardware side.

Whitmore29
Level 3
could file type affect BE turning compression on or not... because i narrowed my selection from my first test just so it would run faster... becasue the first job showed compression as off. and the second one with narrowed scope shows it on. I just dont have the log to show that anymore

Ben_L_
Level 6
Employee
"could file type affect BE turning compression on or not" - No.  Think of compression like a light switch, it's either on or it's off.  It's not selective about giving light to certain things in the room.  Right now we are flipping the switch to turn it on, but the bulb is burned out so nothing is happening.

Whitmore29
Level 3
I will explore some more of the avenues that you suggested, i checked into the SCSI controller its fully up to date as well is the drives firmware from dell. I also have the most up to date driver that Dell offers for the device, I guess ATM i am going to try and install teh Symantec Driver for the device...

Ben_L_
Level 6
Employee
I would honestly go ahead and call Dell regarding the issue and show them the tracer log.  I can't count how many times I've run across this exact issue with that drive. 

Also make sure that the volume you are backing up isn't already compressed, the hardware can't re-compress the data.

Whitmore29
Level 3
The volume isn't already compressed thats for sure,

You have seen this issue with this exact drive before? what did it end up being ?

Ben_L_
Level 6
Employee
the times I've seen the issue before and the tracer log showed compression enabled ended up being a hardware issue.  Either the drive was replaced by the vendor or the controller was replaced.

Whitmore29
Level 3
I still have a hard time understanding how it is a hardware issue when NTbackup to date compresses fine this still points to software to me though what you are saying does make sence if compression didn't work at all.

Larry_Fine
Moderator
Moderator
   VIP   
Ben is right, compression doesn't care about the file type.  But each job can have a different compression setting.  double check your jobs to make sure you are comparing apples-to apples and the setting is the way you want.  Maybe the job that isn't compressing is corrupt... maybe try changing the compression setting, saving the job, then changing it back and saving it?  Or create a new job?

Whitmore29
Level 3
I know this thread is marked as "solved" however it isn't i have been wroking with dell in my absence from the forums here. In anycase they just reaplaced the tape drive today and still we are seeing no compression. Any furthur insight would be greatly appriciated.

Thanks


Chris

Ben_L_
Level 6
Employee
Chris,

I cleared the solution marker.

As for the new drive, does the trace show that compression is being set?

Can you run a backup with software compression instead of hardware compression just to verify the data getting backed up can be compressed?