ntbackup and filecompression

[news_isaac]

We're using ntbackup on a W2Kserver to backup to adr30 tapesm on a
onstream SC50 drive.

Everything went ok until recenty but now ntbackup complains that it
needs a second tape to complete the backup.

The backup set contains an (ntbackup)estimated 18gb dataset (on 3
compressed local drives). The adr30 tape supports hardware compression
2:1 and can contain 15Gb of uncompressed data.

I was wondering if the problem can be that hardwarecompression is not
working properly between the SC50 and ntbackup. On the otherhand i ask
myself if the problem is related to the fact that the serverdrives are
already compessed and there can be no gain in the backup proces (ie
does ntbackup work with the compressed or with the uncompressed
filesizes?)

TIA Isaac,

The Netherlands.

 

[Chris Szilagyi]

Since your drives are compressed, the files will take up less space on
the drive but when you back them up they will occupy their normal size
on the tape (the drive will still compress them as normal). So it is a
little misleading if you are looking at the compressed size of your
drives, since that is not really their native size. Also make sure you
are selecting to use hardware compression within your backup software.
The other possibility is you are trying to back up a lot of files that
cannot be compressed much (i.e. Zip files, JPG images, etc).

Chris Szilagyi
Technical Consultant
______________________________________________________
Apex Internet Solutions - http://www.apex-internet.com
Complete Internet Hosting Solutions, Custom Websites

 

[news_isaac]

Thanx for your reply,

....

Also make sure you
are selecting to use hardware compression within your backup software.

i thought i read somewhere that certain onstream drives do not support
hardware compression when ntbackup is used (i tried onstream support
but it's impossible to reach them at this moment).
Furthermore hardware compression is not in the options/tools dialogbox
in the W2K version of ntbackup. I'll try the /hc option anyhow.

Isaac,

The Netherlands