Minimum capacity compression on LTO 1

[Dani_5]

Hi all!

I' ve got an Adic Faststor 2 library with a HP LTO ultrium drive, and I think this backup device is not working properly with its compression, becouse only I can write on the tapes 180GB with compression.

I Write this standard data from a W2K Server and I don't get put at least 200GB in a data cardtridge.

My question is if, this tape drive could have a compression problem?. If the manufacturer of tapes warrant 200GB with 2:1 compression, why can't I write more data on a LTO Tape?

Thanks in advance for you help, and excuse my English...

Dani.

[Leif Halvarsson_2 · Accepted solution]

Hi,

The 2-1 compression ratio is only an average (and is perhaps what you get with plain text files). Compression ratio is hightly data dependant and I have seen anything between no compression at all (if files is already compressed) to 10-1 or more (log files and database files). 180GB seems quite normal.

PS.
Try pkzip on some of your files to get an idea about compression ratio. It uses an algoritm (LZW) similar to the hardware compression in the drive.

[Dani_5]

Hi Leif,

Thanks a lot for your reply...

Dani.

[harry_7]

Dear Mr. Dani,

Can you let me know. How much time it took for 200 GB Backup.

We are planning to change the date drives from DLT to LTO.

We are using SUN Solaris Oerating System.

Regards

Harry.