Size of backups

If I use Tools>Backup & Optimize I get a backup of 150 MB. If I use Scripts>Export>Backup Archives I get a backup of almost 400 MB. Why is there such a difference? I was anticipating a smaller size for the Archive since it is optimized and zipped; not over twice as large.


I just did a Backup Archive of one of my databases. Here are the comparative sizes:
Database package file: 2.66 GB
Backup Archive file: 640.3 MB

So the backup archive is much smaller than the database package file.

Were you perhaps comparing the size of the backup archive file to the size of an internal Backup folder inside the database package? That’s not an appropriate comparison. What’s the size of your database package file, compared to the size of your backup archive file? The backup archive file holds the contents of your most recent Backup folder (inside the database package), and also the contents of the database Files folder. Note that the backup archive doesn’t contain internal Backup folders. But if you were to open it and start using it, it would then create over a series of Backup & Optimize operations the number of Backup folders specified in your preferences.

I’m not at all sure what a “Database package file” is let alone how to check the size. Is it the file I titled when first creating my database? With that said, I have learned from reading other posts that the Tools>Optimize & Backup results in an internal backup and using the script method creates an external backup - at least I think that is correct. If I understand what you wrote, that is only part of the difference between the two. The internal backup and external do not backup the same data (perhaps an over simplification). The bottom line is that I should probably do both? I had only used the internal backup when I felt it was necessary and then learned about the external backup so figured I better do that on my other hard drive in case of hardware failure. I thought both created the same backup - just that the archive allowed me to choose where to put it and was zipped, which is why I expected a smaller file.

Hope that makes sense and I would appreciate comments to clarify where I still have misconceptions about what I’m doing.


your comments are basically correct. The internal backup creates only copies of the pure database whereas the backup script also backups those files that have been copied to the database package/folder (see preferences).

But the internal backup should be sufficient as the copied files are usually static whereas the database is updated very often (and therefore the likelyhood that a system/harddisc failure, power outage etc. could damage the database is higher).

Christian is correct in noting that the database file (comprised of those ten numbered files inside the database package file and inside the internal Backup folders) is more susceptible to damage than are the files stored inside the database Files folder. If that’s the case, Restore Backup will get you up and running, based on the content the last time Backup & Optimize was run.

But with my typical “belt & suspenders” attitude, I always think about worst cases, including a catastrophic failure of the hard drive. In the worst case, the files inside the database Files folder would be lost, too. That’s why I recommend the Backup Archive script as a very convenient way to create external backups, e.g. on an external drive, CD or DVD. In many years of using Macs, I’ve never had a catastrophic HD failure. But it’s not prudent to take the chance when – in seconds – I can start a script that can protect valuable information. What happens if your laptop is stolen, or your hard drive goes to HD heaven?

And – if you haven’t already guessed – periodically I clone my working HD to an external drive, as well. I was a Boy Scout, once (motto: Be Prepared). On top of that, I was once a Quality Assurance manager for a governmental agency. :slight_smile: