Video Screencast Help

Help required regarding backup Compression

Created: 30 Sep 2012 | 3 comments

Hi I am using BE 2010 R3 and I have HP 1/8 G2 Tape Autoloader (

I use HP 1.6TB LTO tapes.

Compression Type has been selected as "Hardware [if available, otherwise none]" under Tools--Options and also in the properties of Weekly backup job.

Looking into last 3 months our Weekly full backup is between 1,852,309,119,510 bytes to 1,946,504,729,824 bytes. Weekly backup used to fit into 2x1.6 TB tapes when backup was 1.9TB or 1.94TB or 1.85TB data But sometimes even when backup is 1.87 TB or 1.91 TB the backup is taking 3x1.6 TB tapes. Like this weekend it was 1.85 TB and it took 3 tapes. No settings or configurations has been changed in the BE So is this normal ?

1.85 TB
Tape1 - 1:1
Tape2 - 1.2:1
Tape3 - 1:1

1.86 TB
Tape1 - 1:1
Tape2 - 1.3:1

About 1.2TB of data are audio/video/office docs/pdf which doesnt change whereas rest of the data are Server's C: drive, Servers System State/Shadow copy components, 8-10 SQL databases, few gigabytes of office docs/pdf that gets updated regularly.

Any help would be much appreciated, thank you.

Comments 3 CommentsJump to latest comment

CraigV's picture


You won't get any compression on files that are already compressed, eg. video and audio files. These would be 1:1.

Best bet is to read a very good article of pkh's below which explains compression a bit more.


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pkh's picture

When you compressed files like videos, you might end up with more data than you have started with.  This is explained in my article quoted above.  Try turning off compression, you might be able to get more data onto your tapes.

Note that the native uncompressed capacity of your tapes is 800GB.  The 1.6TB capacity assumes a 2:1 compression ratio which is hardly achieved in real-life.

bickyz's picture

thanks CraigV and pkh

By the what made last weekend backup to go over three tapes despite much lower in size i.e. 1.85TB