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differantial backup

Hi

i have a concern on differential backups, this is the situation

will take a full backup to a disk every mondy (scheduled). and differential backup every day to disk (scheduled).

if i take a full backup to a tape on a different day (say month end) out of the schedule and continue the scheduled differential backups, 

what whould be the full backup required to the last differential backup ?

the full backup taken on monday to disk ? or the full backup taken to tape ? (that would be the last full backup taken)

thanks ...

1 Solution

Accepted Solutions
Accepted Solution!

Re: differantial backup

Since the last full backup is the backup to tape, it will be the baseline for all subsequent differential backups.  Just remember the definition of a differential backup which is that a differential backup will backup all additions and changes since the LAST full backup.

Normally, if people needs a monthly full backup, they will substitute it for one of the weekly full backup.  For example, you can schedule the monthly backup to run on the last Monday of the month.  If you add the monthly job to the scheduled job with the weekly full backup and schedule it for EXACTLY the same start time on the last Monday of the month, the monthly full backup will supercede the weekly full backup because it is run less frequently.  The last weekly full backup will not run.

View solution in original post

2 Replies
Accepted Solution!

Re: differantial backup

Since the last full backup is the backup to tape, it will be the baseline for all subsequent differential backups.  Just remember the definition of a differential backup which is that a differential backup will backup all additions and changes since the LAST full backup.

Normally, if people needs a monthly full backup, they will substitute it for one of the weekly full backup.  For example, you can schedule the monthly backup to run on the last Monday of the month.  If you add the monthly job to the scheduled job with the weekly full backup and schedule it for EXACTLY the same start time on the last Monday of the month, the monthly full backup will supercede the weekly full backup because it is run less frequently.  The last weekly full backup will not run.

View solution in original post

Re: differantial backup

As well as pkh suggestion, the other option is to duplicate the full from disk to tape (instead of runnign a direct tp tape job) which leaves the chain for the differential intact.