Backing up with compressions, configuration and what to compress?

Posted on 2004-11-04
Last Modified: 2010-08-05
Lately I have had problems with backing up due to lack of space on the HP DDS 4mm Cartridge 40GB. I`m running Windows 2000 server and Windows Exchange server. Using Backup Excec v 8.6 rev 3808
For Instance the C: disk has not enabled compress drive to save disk space
On the other hand Backup Excec has enabled Hardware Compression.;

Device tab, properties for HP1, configuration tab. Hardware Compression is enabled

Have I understood it correctly that Backup Excec wil not compress data, unless I have enabled compress drive to save disk space on for instance the C: disk?

Will it help to compress drives. Would it Cause any problems, if so: which drives should be or not be compressed? What about M: or D:

Which Block size , buffer size , buffer count, high water count should I use? And why
Question by:TorgN
    LVL 15

    Expert Comment

    Usually, when you backup data to tape, it's always in compressed mode, and not in Native Mode, such as when you backup to CD.

    I'd suggest that you leave all those options: Which Block size , buffer size , buffer count, high water count... as they are by default.

    As always, you can try visit : " "

    Best Regards!
    LVL 10

    Expert Comment

    Compressing drives is never a option for me. It only causes file and data corruption. Try spanning over to a second disk or if the hard drive is cluttered up, try adding a secind drive.
    LVL 32

    Accepted Solution

    Hi TorgN,

    The DDS tape you're talking about has a native size of 20GB, the compressed amount of 40GB (as in 2:1 compression) is rarely reached.
    Most likely you have over 20GB of data to backup at the moment and the compression is less then 2:1, so your tape is indeed full.
    A lot of filetypes can't be compressed much, like jpg, avi, exe, but also allready compressed items like rar, tar, zip etc.
    Things that can be compressed a lot are databases and plain text documents.

    What you can do to back this all up is to do a full backup in the weekends (using two tapes) and differential backups on every day of the week.



    Author Comment

    Thanks for good answers. Although I had hped to avoid using more than 1 tape per backup.
    The tape stopped at 35GB before it demanded a new tape to continue. I have excluded all temprary files and such in hope to reduce amount of data to backup. But.....nooooo. As far as I can tell it is around 2 or 3 GB to much data for having a sucessfull backup with only one cartridge (C5718A). But in a last desperate attempt in reduing the amount of work for me....isn`t there any large files/folders in WINNT or in the exchange that are not critical If I ever would have to use the restore form Tape?
    I`ll  probably have to do what LucF says,
    LVL 32

    Expert Comment

    by:Luc Franken
    35GB on a 20/40 tape is pretty good :) I normally only reach about 1.5:1 compression.
    Only you know what you can exclude from the backup... maybe some downloads stored somewhere? Back them up on cd-r or DVD-R and exclude them. etc, etc.


    Author Comment

    Good Idea.... Tank you
    LVL 32

    Expert Comment

    by:Luc Franken
    Glad to help :)


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