Differential vs Full Backups in regards to file versons
I need some help in thinking a situation through re Differential backups.
I'm running Veritas BackupExec 8.6 on a DDS-4 drive. I'm currently doing daily full backups of around 100 gig and am considering switching to a differential backup as follows:
Mon: Full Backup
Tue: Differential
Wed: Differential
Thur: Differential
Fri: Differential
My question is this. Monday's backup will contain Document A and is revised throughout the week; thus, the revisions are captured on the differential backups.
I should add that the backup will capture the revision that is available at the time of actual backing up since several revisions can occur between backups. I understand that if I want to backup all revisions - regardless of their usefulness - that I would need a real-time mirroring situation to a separate NAS unit.
Lets say that on Fri I delete Document A and want to restore it from the backups but of course will not know which tape(s) contains THE MOST RECENT VERSION of Document A. How does BackupExec determine this? Do I start from Monday's backup and select Document A? Will BackupExec tell me that a newer version is available on another differential tape?
Isn't doing the daily FULL backups the same as doing differential? Aside from it taking much longer, FULL backups will still backup Document A.
You see where I'm going with this? What is the point of doing differential backups from a revision control point of view (ignore the time saving part)? If Document A is still being captured at the time of the backup - Full or Differential - then it means the backup is still doing "revision control".
I'm running Veritas BackupExec 8.6 on a DDS-4 drive. I'm currently doing daily full backups of around 100 gig and am considering switching to a differential backup as follows:
Mon: Full Backup
Tue: Differential
Wed: Differential
Thur: Differential
Fri: Differential
My question is this. Monday's backup will contain Document A and is revised throughout the week; thus, the revisions are captured on the differential backups.
I should add that the backup will capture the revision that is available at the time of actual backing up since several revisions can occur between backups. I understand that if I want to backup all revisions - regardless of their usefulness - that I would need a real-time mirroring situation to a separate NAS unit.
Lets say that on Fri I delete Document A and want to restore it from the backups but of course will not know which tape(s) contains THE MOST RECENT VERSION of Document A. How does BackupExec determine this? Do I start from Monday's backup and select Document A? Will BackupExec tell me that a newer version is available on another differential tape?
Isn't doing the daily FULL backups the same as doing differential? Aside from it taking much longer, FULL backups will still backup Document A.
You see where I'm going with this? What is the point of doing differential backups from a revision control point of view (ignore the time saving part)? If Document A is still being captured at the time of the backup - Full or Differential - then it means the backup is still doing "revision control".
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So are we all in agreement that the only difference between FULL and DIFFERENTIAL backups is the time saving factor?
The revision control factor is still the same because changes to a document BETWEEN BACKUPS are not captured on either backup scenario. Sure one could increase the frequency of the DIFFERENTIAL backups but what's the point? You will be taxing your systems at the time your users are depending upon it for their productivity use - not server backup use!!
Besides, isn't the main purpose of any backup scenario so that it fulfills one key business continuity criteria: to have the most recent snapshot of data available should something go wrong (natural, digital or user initiated)? One should not depend upon a backup for revision control. Like this thread has said thus far, go to the software applications for revision control.
What are your thoughts regarding this?
The revision control factor is still the same because changes to a document BETWEEN BACKUPS are not captured on either backup scenario. Sure one could increase the frequency of the DIFFERENTIAL backups but what's the point? You will be taxing your systems at the time your users are depending upon it for their productivity use - not server backup use!!
Besides, isn't the main purpose of any backup scenario so that it fulfills one key business continuity criteria: to have the most recent snapshot of data available should something go wrong (natural, digital or user initiated)? One should not depend upon a backup for revision control. Like this thread has said thus far, go to the software applications for revision control.
What are your thoughts regarding this?
Agreed. Although I would also say that most backup/restore strategies less than satisfy that criteria you mention above. In fact they provide a compromised solution as the point in time is usually not sufficiently up to date for some people. You get what you pay for I guess.
Barny
Barny
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andyalder - ouch! You've got to drive the stake in deep don't you? Yes, 8.6 is ancient and it has served our needs until the topic of revision control came up.
I agree with IPKON_Networks , you get what you pay for.
I would advise upgrading to v10, since 8.6 was pretty buggy for some stuff.
I would advise upgrading to v10, since 8.6 was pretty buggy for some stuff.
Differential will contain all the changes up until your last full backup.
backup exec should show you all versions available on your cataloged media, and you can choose which one to restore.
I hope this helps !