About backups, data compression and read/write errors

Hi. I am unsure of which method of backing up the contents of my HDD is better: in compressed (e.g. .zip) or uncompressed format.

For the compressed format:

  1. Less space hence CDs required.
  2. Faster completion times.


  1. Higher information density due to compression means that read/write errors, due to media, for example, would be more severe than uncompressed format. Having 1 byte of corrupted compressed data means you lose more than 1 byte of uncompressed data.
  2. The archive may not work at all. Then all your data is lost. But in uncompressed format, a corrupted file here and there is pretty isolated, it would not corrupt the rest of your stored data.

For the uncompressed format:

  1. Slower completion times.


  1. Because you involve more CDs in your backup process, this means that you increase the risk of corruption due to the occasional media defect.
  2. With more CDs involved, even though the errors would be contained to the affected files, it would be a major pain to shuffle backup and backup of backup CDs to get all the files.
  3. More space hence CDs required.

Which is the best means of data archival?

Originally posted by Devils Advocate
For the uncompressed format:

  1. More space hence CDs required.

I’m sure that’s a “pro” if you manufacture CDs, but for me it would be listed under “contra” :wink:

I myself burn everything uncompressed. Just because empty CDs are cheap, and so you can always retrieve your data without using other programs.

Heh, whoops I copied and pasted from the top one and didn’t change that bit properly. Thanks for pointing it out.

Neither backup method is “better”. It’s a matter of choice based on the pros and cons that you mentioned.

The primary advantage of a compressed backup is less media usage.

The primary disadvantage is compression requires more time.

Data corruption does not have to be an issue if the backup is verifed.

Personally I would use a compressed backup. Disc imaging programs make images using high compression with reliable results.