[AccessD] Backup routines

On 24 Feb 2004 at 8:59, Carlos Alberto Alves wrote:

> Dear Members:
> I would like to have your input on this subject. I wrote a Sub to execute 
> regular BE backups. Everyday thru a month a BE copy is compacted 
> (DBEngine.CompactDatabase) and renamed and stored in a different folder. 
> Do you think that such a 30-day backup routine is overzealous???

Depends on the application and why you are backing up.

Several possible reasons:

1. To keep historical records which you can refer back to.

2. To provide fallback if you discover that data has been "messed up" 
(bad data entry, incorrect deletions etc)

3. For data entry audit purposes

4.  For data recovery in the event of a major disaster


For Type 1 - Some accounting applications, keep monthly/annual 
backups that go back years.

for Type 2 - it depends on how long you expect it to take to discover 
such errors 

for Type 3 - similar reasoning to type 2

for Type 4, you don't need to store more that a single generation as 
long as you are sure it is retrievable.

Ask yourself why you want the 20 day old copy for example. 
If you have the 21 day old copy and the 19 day old copy, is there 
*any* reason you would ever want to access or restore the 20 day one?
If the answer is No, there is no poiont in maintaining such as long 
line of backups.

A common way of covering these contingencies is something like:

1. Save daily backups which you normally delete after a week
2. Keep a weekly copy for more than a month
3. Keep a monthly copy for more than a year
4. Keep an Annual copy permanently.

You can do this by checking the data and doing appropriate file 
deletes 

One way would be:

If it's a Friday,  delete previous Friday files if they are a month 
old else delete any files that exactly  a week old.

If it's the first of the month delete files that are more than 12 
months old  unless they are dated the 1st Jan (or whatever)

That means that you will have less than 30 copies but would have a 
much better archive.
 
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