Storagetek L20 Ultrium 2 compression??

[ErnestScribbler]

Hello to all board members - This is my first post and I hope you can help with my query.

We have a Storagetek L20 with dual HP Ultrium 2 drives and are having problems getting the tapes to compress.

Basically when we set the tape device up and ran the storagetek configuration utility for the L20 the device it would not pick up that we had ultrium 2 drives within the device but Ultrium 1. After double checking that the drives were actually ultrium 2 we contacted our supplier for support. Now, after speaking to our suppliers so called storagetek specialist he advised us to pay know attention the stoagetek configuration utility and to just install our backup software (Netbackup 5.0 win2k) and this will configure the tape device.

OK, we said... He was right in that the netback installation did indeed detect the stoagetek device and correctly recognised that the ultrium 2 drives within the tape device.

Now the problem... We do not get any compression on the 200g tapes what so ever. We have configured the compression within netbackup, which I think has nothing to do with the compression on the physical tapes - more to do with client side compression? (Please correct me if I am wrong). Am I not right in thinking that the tape drives should automatically enable compression due to the amount of data written to the tape?

So can any of you shine a light on what maybe the problem - is it incorrect firmware on the device? The storagetek web site is not much help at all...

Many thanks in advance

 

[tapedrivedoctor]

It sounds as if the drives are performing as LTO1's. Make sure you have the latest Library Firmware to recognise the drives as LTO2's.

 

[Pachtva]

The configuration of L20 does not affect the settings of the tape drives.

STK configure the tape drives that comes with your library, and sets the default configuration of the LTO tape drives. And this is "compression: enabled".

Then, the only reason can be the follow things:

1: the data that you´re backup cannot be compressed any more. Make a probe with a job with only .txt files. This kind of info can be compressed.

2: Look in the settings of the software and enable "hardware compress".

3: You can download a tool from de

http://www.hp.com

site, in the seccion of support - storage. MAke a search "LTO ultrium" and you can find at least 4 sofware tools in which you can configure this settings in the tape drive if you want. BUT REMEMBER THAT THE DEFAULT CONFIGURATION ITS COMPRESS "ENABLE"

 

[letournp]

Hey !

We previously had BackupExec and had to change to NetBackup because the backup window was too long (now with multiplexing we reduced by 3 times the backup time)

We also have a compression problem.

BackupExec is still installed: when we take the backup with backup exec we manage to put up too 165Go on on tape
IBM 57p6717 LTO Ultrium-1 100/200

Using the same backup selection with NetBackup, we manage to put a maximum 106Go

Same computer, same tape, same driver(up to date), same firmware(up to date)

I'm puzzled !

 

[cnozz]

Multiplexing takes up more space on a tape beacuse of the (MH) Media Header Size and the (BH) Backup Header Size which should be about 1024bytes/1K per MH and BH. This could get rather technical but if you read your Netbackup Administrators Guide and lookup Multiplexing it should help explain it to you. In my rather old guide here it doesn't really come out and say that multiplexing takes up more tape space but it leads to reason since the system has to have a way to index the various streams of data going to it. Let me know if you have any other questions.

Chris Nozz