Incremental Backup using one DLT tape.

Posted on 2005-04-16
Last Modified: 2013-12-27
Hi All,

I recently posted a question on how to perform incremental backups and restores at:

I tried it with multiple tapes and everything worked fine. The question is: can I do it with one tape? Just make backups and not rewind?

Here are the partitions I have:

ufsdump 0ucf /dev/rmt/0n /
ufsdump 0ucf /dev/rmt/0n /var
ufsdump 0ucf /dev/rmt/0n /mnt1
ufsdump 0ucf /dev/rmt/0n /mnt2
ufsdump 0ucf /dev/rmt/0n /mnt3

Assuming I want to make a level 0-7 backup and I want to restore something from level 4, can it be done on the same tape?
Question by:kalmen
    LVL 10

    Accepted Solution

    basically yes.

    However you should not keep the tape in a non-rewinded state for a long time. What you can do is the following:

    You start with:

    ufsdump 0ucf /dev/rmt/0n /
    ufsdump 0ucf /dev/rmt/0n /var
    ufsdump 0ucf /dev/rmt/0n /mnt1
    ufsdump 0ucf /dev/rmt/0n /mnt2
    ufsdump 0ucf /dev/rmt/0 /mnt3

    then when you want to add the incrementals

    mt -f /dev/rmt/0n fsf  5
    ufsdump 1ucf /dev/rmt/0n /
    ufsdump 1ucf /dev/rmt/0n /var
    ufsdump 1ucf /dev/rmt/0n /mnt1
    ufsdump 1ucf /dev/rmt/0n /mnt2
    ufsdump 1ucf /dev/rmt/0 /mnt3

    the mt-command is used to control the tape  fsf 5 means fordward 5 sessions (getting you to the end of the full backup.

    if you want to do an increment of the increment (or in other words everything that changed since the last incremental) you'd do

    mt -f /dev/rmt/0n fsf  10
    ufsdump 2ucf /dev/rmt/0n /
    ufsdump 2ucf /dev/rmt/0n /var
    ufsdump 2ucf /dev/rmt/0n /mnt1
    ufsdump 2ucf /dev/rmt/0n /mnt2
    ufsdump 2ucf /dev/rmt/0 /mnt3

    Even though this is technically possible I would not recommend it to much, because restoreing such a thing might get quite complicate.

    LVL 1

    Author Comment

    Pefect. Thanks.

    Featured Post

    What Is Threat Intelligence?

    Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

    Join & Write a Comment

    Installing FreeBSD… FreeBSD is a darling of an operating system. The stability and usability make it a clear choice for servers and desktops (for the cunning). Savvy?  The Ports collection makes available every popular FOSS application and packag…
    FreeBSD on EC2 FreeBSD ( is a robust Unix-like operating system that has been around for many years. FreeBSD is available on Amazon EC2 through Amazon Machine Images (AMIs) provided by FreeBSD developer and security office…
    Learn how to find files with the shell using the find and locate commands. Use locate to find a needle in a haystack.: With locate, check if the file still exists.: Use find to get the actual location of the file.:
    In a previous video, we went over how to export a DynamoDB table into Amazon S3.  In this video, we show how to load the export from S3 into a DynamoDB table.

    729 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    16 Experts available now in Live!

    Get 1:1 Help Now