compression ration ? single instance

[superfred]

I use backup exec 2010. I am backing up on LTO tape 200 gig.

I am backing up 170 gig of data and it tell me my use capacity is 160 gig. My compression ration is 1:1:1

what does it mean?
should I use software compression ?
How can I know what is my compression ratio vs my single instance files.

Fred
superfred@advanatgesport.com

[Ken_Putnam]

Are you using LTO-1 tapes (100/200) or LTO-2 tapes (200/400)?

If  LTO-1 you are actually getting about 1.7:1 compression (which is quite good, I usually estimate about 1.2-1.3:1 until a specific job has run several times and I can get an average.)

If you are using HW comression. the compression is listed as 1:1 because BackupExec has no way of knowing what compression the drive is getting.  SW compression will not be exactly the same, but will usually be quite close

[pkh]

I am backing up 170 gig of data and it tell me my use capacity is 160 gig. My compression ration is 1:1:1

This means that you output 170GB of data to your tape drive and it compressed this data to 160GB, thus achieving a compression ratio (output data / data on tape) of 1.1:1.  The compression in your case is done by the hardware, i.e., you are using hardware compression.

If you use software compression, BE will compress the data before it is output to the tape drive.  In this case, you would probably find that the data that is sent to the tape is 160GB and the used capacity is 160GB.  The compression ratio when you click on the media would show as 1:1 because the hardware cannot compress compressed data further.

I find that software and hardware compression achieved roughly the same compression ratio.  However, software compression takes slightly longer as BE has to do the work of compressing the files.

The above is the overall compression ratio for all the data that was backed up.  If you want to know each individual file's compression ratio, you either back it up individually or zipped it up.