Tidying up old backups

[f1charlie]

I have the automatic backup set to run every day at midday, saving to my external hard drive, and this has been working fine (I think as I have never tried to restore anything!). As some of these backups were a few months old I thought I would do a bit of tidying, so I deleted some of the older sets.
Todays backup failed. The only way I could get the daily backup to work was to create a new full backup first.
So, is there any way of deleting old backups without creating a new full backup first?

 

[OldBloke]

It depends what backup program you are using and in particular what method - (full, incremental, differential, etc)

If it's a full backup every time, you should be able to delete any of the older backups you wish.

If it's differential (a set starts with a full backup, then each subsequent backup records all the changes since that full backup) you can delete any of the differential files, just don't delete the full backup which started the set.

If it's incremental (the set starts with a full backup and then each subsequent backup only records the changes since the previous incremental backup) you can't delete even one of them or you break the chain.

"As some of these backups were a few months old I thought I would do a bit of tidying, so I deleted some of the older sets."

If you delete a complete set, it should not disturb any other sets. When you deleted them maybe you accidentally deleted part of the current set, in which case the next daily incremental should show an error message because one or more of the current set is missing.

Or another possibility: Maybe it went wrong because you deleted it using Explorer and the backup program prefers you to delete sets using its own interface, so it can keep track of what's going on. If so, it's not a very robust program because it should be able to adjust to that.

Anyway, maybe it's just as well you began a new set starting with a full backup, which you should do occasionally. Otherwise incremental sets can grow very long, with many files, every one of which is necessary if you ever need to do a complete restore.

"I have never tried to restore anything!"

That's a worry.
Like having a fire drill occasionally to test the alarms and procedures, you should do a test restore of a new backup system at least once after you start using it. For a test restore, you don't restore to the main data disk which you have been backing up, in case the restore doesn't work properly and you scramble the original files. So you restore to a spare disk and then compare that to the main disk.

 

[f1charlie]

Thanks for the comprehensive reply OldBloke.

This is using Vista's very own backup, so the automatic backups must be incrementals. I had thought I had seen somewhere that I could just delete the intermediate backups, but I am obviously mistaken (or the information was).

I had wondered why every incremental backup was stored within a folder called 'Backup Set 2008-06-10', but having created a new full backup I can see that this is created from the full backup and is obviously necessary to create the incrementals and I have broken the chain by deleting some.

I also use Maxblast to create separate image backups every so often independently of the Vista backup.

 

[OldBloke]

"Thanks for the comprehensive reply OldBloke."

You're welcome

I had wondered why every incremental backup was stored within a folder called 'Backup Set 2008-06-10',

It seems Microsoft's backup program is using the word "set" in a different way from what I am used to. Maybe it works like this: They are calling a daily incremental backup in one of those dated folders a "set". But that daily "set" is dependent on previous daily incremental backups, back to whichever of the dated folders contains a full backup which started the series. Let's use the word Series for a full set of those daily sets

If that guess is correct, you have just started a new Series of backups.

If you have broken a previous series of incremental backups, by deleting some of its intermediate folders, you could now delete the rest of that series if you wish. Probably an incomplete series can still be used for making partial restores (some selected files) but it certainly can't be used for a complete restore to the state which existed at the time of the last one in the series.

I haven't used Vista's own backup program (I've used non-Microsoft backup programs) so please be aware that what's written above is a guess about what is happening, based on what you told me.

"I also use Maxblast to create separate image backups every so often independently of the Vista backup."

That's a very good idea. I hope you have made a bootable CD of the MaxBlast program (you can do it using the "make bootable media" command from its menu). That is essential to be able to restore the system from your backup image if Windows becomes unbootable.

 

[f1charlie]

Thanks once again OldBloke for taking the time to reply - at least I have supplied you with an additional piece of (probably useless) information on the vagaries of Vista backup!

I will delete that backup set which I have broken.

And I have indeed made my bootup CD for Maxblast.