Comparing different compression levels in Acronis backup software
Acronis True Image Home, or simply “Acronis” for short, is a backup utility which allows you to create an “image” of your entire system which you can then use to restore your system to the exact state it was in when the image was created. If you are familiar with Symantec’s Ghost software, it is very similar.
This isn’t a post about how to backup data or how to use Acronis; rather it is simply a comparison of the different compression options provided by Acronis.
Among many options, Acronis allows you to choose the compression level of the backup image being created. Additionally, Acronis allows you to choose whether you want to validate the backup image once it has been created. I set out to determine the cost in time and hard drive space for each combination of compression and validation.
Test System
I used my 4 year old Dell 700m laptop as my test system. This laptop has a 1.6 Ghz Pentium M with 2GB of RAM. I formatted the system and installed a fresh copy of Windows XP Pro with all the updates. The laptop has a 60GB IDE drive which is formatted into two partitions; 35GB and 22GB (with 3GB lost to the hard drive fairies). Windows XP with Service Pack 3 and all other updates takes up 5.95GB of the 35GB partition. All backup operations used the 35GB partition as the backup source and the 22GB partition as the backup destination.
I used the boot CD created by version 11 of Acronis to do all backups and restores.
Results
| Compression Level |
Estimated Size |
Estimated Time |
Backup Size |
Backup Time |
Backup Time w/ Validation |
Validation Cost |
Restore Time |
|---|---|---|---|---|---|---|---|
| None | 5.95 GB | 20min | 3.96 GB | 11min 12sec | 15min 52sec | 41% Time Increase | 11min 21sec |
| Normal | 3.56 GB | 8min | 2.46 GB | 8min 43sec | 11min 40sec | 33% Time Increase | 10min 48sec |
| High | 3.11 GB | 7min | 2.15GB | 9min 8sec | 11min 58sec | 31% Time Increase | 10min 17sec |
| Maximum | 3.04 GB | 10min | 2.10 GB | 13min 55 sec | 17min 9sec | 23% Time Increase | 10min 40sec |
Column Explanation
Compression Level: The level of compression chosen
Estimated Size: The size of the backup image estimated by Acronis before staring the backup process.
Estimated Time: The amount of time Acronis estimated it would take to complete before starting the backup process. (Note: Acronis does not increase the time estimate when validation is selected)
Backup Size: Actual size of the backup image.
Backup Time: Actual amount of time the backup process took without validation.
Backup Time w/ Validation: Actual amount of time the backup process took with validation.
Validation Cost: The percentage of time increased by selecting to validate the backup image.
Restore Time: Amount of time the restore process took. (None of the backup images were validated before restoring.)
Conclusion
Many variables come into play when benchmarking a backup utility. The speed of the processor, the size of the data being backed up, the composition of the data, and the media used as the backup destination are among many variables which can vary backup times and sizes. That is why this should not be viewed as a benchmark of Acronis itself, but rather a benchmark of the different options within Acronis as compared to each other.
Here are some findings from this comparison test.
- Even with no compression chosen, the resulting image was smaller than the original data size.
- Validation cost decreases as the compression level increases. This is likely due to the smaller file being validated.
- Maximum compression provides a very small decrease in file size compared to the large increase in backup time. If time is an issue, maximum compression is not worth it.
- Increasing the compression generally decreases the restore time, except when maximum compression is chosen.
- High compression is the best all around option. You get a decent amount of file size decrease as compared to normal compression for not much more time increase. Plus it provides for the fastest restore time.