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Supplementing weekly backups with daily incremental backups?


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So, every weekend I want to back a server up to tape. I've got a media set full of tapes named Weekly Backup. I want to perform daily backups during the week too but I don't want to juggle tape sets every day. Is there some way to tell Retrospect: "Every day during the week perform a backup to this external hard drive but ONLY back up the files that have changed since the last time we did a backup to tape."

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I don't think so, and even if you could, I'm not so sure you'd really want to.

 

If you run the backup to both disk *and* tape, you get two copies of the backup, and if you have to

retrieve, it'll happen at high speed. (tape is always slower) How would you manage the synchronization between the "mixed-media" media set?

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This is a capability in the Unix dump backup program. Backups are done at "levels", and a backup at one level backs up everything that has changed since the last backup of a lower level. Ten levels [0..9] are supported. Level 0 always backs up everything.

 

To restore a single file, the most recent backup tapes are searched from highest to lowest numbered level, and the restore is finished when the file is found (finding the most recent copy of the file as quickly as possible). To restore a whole file system a directory subtree, the backup is loaded from the lowest numbered to the highest numbered level (each one overwriting modified files).

 

Retrospect effectively does a "level 0" backup the first time a media set is used or when it is recycled, and then increments the "level" for every backup after that (but it's almost certainly not implemented that way).

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So, every weekend I want to back a server up to tape. I've got a media set full of tapes named Weekly Backup. I want to perform daily backups during the week too but I don't want to juggle tape sets every day. Is there some way to tell Retrospect: "Every day during the week perform a backup to this external hard drive but ONLY back up the files that have changed since the last time we did a backup to tape."

You should do a disk-to-disk-to-tape backup, see below.

 

Vocabulary:

You always backup to a media set. Media sets has members such as disks and tapes (depending on the type of media set).

 

Here's how to set it up in three steps:

(1) Backup to a disk media set every day. Set the disk media set to allow grooming and decide how many backups to keep. (We backup every weekday and keep 5 backups, so we always have the last week's backups readily available.)

(2) Create a "Copy backup" script that copies the last backup of each source from the disk media set to the tape media set. Schedule it once a week (for instance).

post-8868-0-40610500-1359706554_thumb.png

(3) Create a "Groom" script that grooms the disk media set every weekend.

 

We have been doing this for years (in the Windows version of Retrospect) and it works fine.

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You should do a disk-to-disk-to-tape backup, see below.

 

Vocabulary:

You always backup to a media set. Media sets has members such as disks and tapes (depending on the type of media set).

 

Here's how to set it up in three steps:

(1) Backup to a disk media set every day. Set the disk media set to allow grooming and decide how many backups to keep. (We backup every weekday and keep 5 backups, so we always have the last week's backups readily available.)

(2) Create a "Copy backup" script that copies the last backup of each source from the disk media set to the tape media set. Schedule it once a week (for instance).

post-8868-0-40610500-1359706554_thumb.png

(3) Create a "Groom" script that grooms the disk media set every weekend.

 

We have been doing this for years (in the Windows version of Retrospect) and it works fine.

 

Hmm, this idea sounds promising. The only thing I wonder about is step two. If it's copying the latest backup from the disk media set to the tape media set is this just a straight copy? In other words, if the backup on the disk media is around 5TB is it going to copy all 5TBs to tape every weekend or can it compare the two and copy only what's changed?

 

Thank you all for your replies to this topic.

 

EDIT: Sorry, I should have tried checking the manual again before I asked that question. It seems when copying backups retrospect does compare the source and destination and copies only what's different.

 

By default, copying backups matches files in the source to files already in the destination and only copies the necessary files. Existing backups and point-in- time file/folder listings already present on the destination Media Set remain untouched.
Edited by JamesM
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