Cobian Backup

Cobian Backup is only available for Windows but it has versions from every version of Windows from Windows 95 to 7. Cobian Backup is a good choice for a simple backup of a Windows machine. You could backup to a non windows machine using a file share. Version 8 of Cobian Backup is free and open source. Later versions are free but not open source.

Versions

The main versions are 7, 8, 9, and 10. Cobian backup 10 is the current version and works on Windows from 7 back to XP, both 32 bit and 64 bit, but is not open source. Cobian Backup 9 works on Windows from Vista back to 2000 but is not open source. Cobian backup 8 works on Windows from Vista back to NT and is open source. Cobian backup 7 works on Windows from XP back to 95. Version 8 offers the most features in an open source version. Your choice of operating system might force you to use a different version.

Version 9

I started with version 8 on Windows 2000 then used 8 on XP then changed to 9 on XP to try out some new features. There are a lot of new features in 9 including volume shadow copies, 7-zip, and you can backup locked files. The 7-zip compression format saved a little bit of space but used more than twice as much time, making my main backup impractical. The splitting of a compressed backup into DVD size chunks did not work. I gained nothing by switching to version 9.

Version 10

Version 10 is supposed to be 200% faster than version 9 and 8. I switched to version 10 to get the extra speed. Version 10 produced similar times to version 9 and 8 for my most important backups. Version 9 did crash in one test and version 10 did not crash in the same test, making version 10 more reliable than 9. The test producing the crash was only an experiment and was not part of my regular backups. Again I gained nothing from upgrading from version 8. Your results might be different.

You will need version 10 for Windows 7 and you may benefit from version 10 working in 64 bit mode if you have a 64 bit version of Windows. I have only two Windows computers left to backup. Both are XP. One is 64 bit. I use version 10 on the 64 bit machine because 9 crashed in one test and I cannot be bothered switching back to version 8. I use the same version 10 on the 32 bit machine purely to work with one version instead of two.

Options

Select Tools, Options, General, and switch off automatic checking for updates. That is one more slow down you do not want when starting your computer. You can manually check once per month during one of your quiet times.

Chunking

You can split the output backup into chunks to fit on optical media. I want to backup from disk to disk, for speed, then copy the backup to rewritable DVDs for safe storage at another site. The split files did not work. I could not access the files in the chunks. Corbian backup provides a special decompressor for split files and the decompressor returned only a few of the files. The latest 7-zip reads split files and could not access files in the Corbian backup chunks.

The whole idea of splitting the files was to backup to optical disk. Regular disks are now so cheap that I will run my large backups to removable regular disks perhaps using an eSata connection or the new USB 3.0. BluRay disks are falling in price slowly. SDHC cards are falling in price faster. New notebooks have slots for SDHC cards, making SDHC cards a better choice than BluRay disks. I will give up on splitting compressed files.

Compression

You can compress the backup to save space. Corbian Backup 8 offers Zip compression. Corbian Backup 9 offers Zip and 7zip compression. 7zip uses less space so I switched from version 8 to version 9. 7zip compression is limited to chunks of 2 gigabytes and does not work with the 4.7 GB DVD option. I had to switch back to Zip compression to get DVD size chunks.

7zip required 34 minutes to squeeze my 4.7 GB system partition into a 1.23 GB backup. Zip used just 13 minutes to squeeze the same partition into a 1.55 GB backup. The time saved by Zip is more important than the extra backup space required because I need to backup a partition 50 times bigger than my little test. A 25 hour backup is not acceptable.

7zip uses more processor time and less memory than Zip. On a dual core 2.11 GHz processor, 7zip did not use all the available processor time because the processing was limited by disk speed. Zip used 200% more memory but was still using a lot less memory than what was available.

Cobian Backup 10 is 200% faster according to the developer. I tried version 10 just for the extra speed and did not see a difference for the options I am using. Version 10 worked on one test where version 9 locked up so I will continue using 10 for the reliability.

Cobian Backup 9 defaults to Zip level 6 and 7zip using LZMA compression at the 7zip normal level. You can set either to use more processor time to produce smaller backups.

Exclude files

When you set up a backup task there are usually files you can exclude. The Windows paging file is one. When you backup the system partition, select your backup task then Edit task then Special. Select the Add button under Exclude these files. Select Files then select c:\pagefile.sys.

Incremental backups

Your first backup of your computer should be a full backup of everything. After the first backup, you can perform an incremental backup where only changed files are backed up. You can restore a file from the latest incremental backup containing the file you need. Every so often you have to perform a full backup again because it is difficult to restore a set of files from many incremental backups.

Cobian Backup can perform a full backup for the first backup in a set of incremental backups. You define an incremental backup. Corbian backup makes, by default, the first backup a full backup. There is also an option, in recent versions, to put the backup type in the file or directory name for the backup. When you go through a set of backups, you keep all backups back to and including the most recent full backup.

What I did not find was an option to repeat the full backups at regular intervals. A nice feature would be to start every month with a full backup then start each day with an incremental backup. You might have to schedule two separate backup tasks.

Execution time

I tested the backup options using three tests typical of your first full backup.

Compression options

The backups are fast when performing a raw copy because I use fast disks. A low level of compression produces big reduction in backup size using only a small amount of computing power when the files are text or code. My largest directories are full of photographs that do not compress and may end up slightly bigger when compressed.

The next reduction in size through compression uses a lot of processing power no matter what type of compression you use. The default middle Zip setting is faster than the default middle 7zip setting. An interesting comparison would be to use some of the other Zip and 7zip settings. I did not spend time on further detailed experiments because consistency across several computers is more important than producing a minor performance enhancement for one computer.

Some files are already compressed. A lot of modern document files are saved compressed. Look at an OpenOffice file using the 7zip archive browser. Their .odt file contains several XML files and folders compressed into one archive. You will not reduce the size of these files using standard compression.

Some files do not compress. Binary image files are hard to compress unless they contain large areas of flat colour stored in a repetitive internal format. PNG files are already compressed using Zip and become 3 percent larger when compressed again during the backup. Corbian Backup excludes some files from compression but not .PNG files. Add .PNG files to the exclusion list.

Photographs rarely compress. Note that JPEG provides something they call compression but it squashes down the size of an image by squeezing out the quality. JPEG call their destructive processing compression but it is closer to the way car bodies are crushed for shipment to a scrap yard.

In my tests TIFF files compressed 37%, DLL files 49%, PDF files 16%, and PSP files 32%.

Backup 4.7 gigabytes

The first test backed up a partition containing 4.7 GB of mixed data and program files on drive c:. The task backup up all the files on drive c: except the page file and some temporary directories. A backup with no compression used 4 minutes, the default Zip compression used 13 minutes, and the default 7zip compression used 34 minutes.

Backing up with no compression is the fastest and uses a lot of disk space but disk space is so cheap that you might not need to think about it for such a small backup. The result would also fit on a DVD with no compression. The only requirement to make this work with no compression then to fit on a DVD is to exclude all those temporary files hidden in strange places by a design fault in Windows.

Backup 18.4 gigabytes

Version 10 with the default Zip settings used 1 hour and 4 minutes to backup 18.4 GB of mixed files. I did not test 7zip because the output has to be in DVD size chunks and 7zip does not handle DVD size chunks.

The big test, 356 gigabytes

My third test is a backup of a partition containing 356 GB of data in 522,874 files. My test partition contain mixtures of text, documents, code files, images, databases, and everything else. Most of the files should compress by a large amount and most of the compressible files are small text files that will not make a big difference to the overall size.

The backup consumed 29 hours, 59 minutes, and 48 seconds! That is from the default Zip settings and is too long. The result was 77 DVD size chunks. The chunks added up to 323 GB, a saving of only 9 percent. The Zip option has a list of files that are not compressed, because they are already compressed, but the file exclusion list is missing many common file formats including .png.

I ran the same backup without compression and it used 8 hours, 26 minutes, and 23 seconds, making an overnight backup practical.

USB 2.0

The backup tests were to a USB 2.0 disk drive. USB is fast for continuous transfer of the data in large files and slows down each time you open a file. The best way to perform a full backup on your desktop computer would be to install a spare disk and backup direct from disk to disk to minimise the disruption. You could then transfer the backup from the spare disk to your USB disk in the background while you work on the computer.

USB 3.0 is on the way and is faster for data transfer but may not help with the slow file open process. The USB 3.0 cables will be shorter and may limit your options for hiding the backup disk.

eSATA is already here and should be as fast as a local disk. Not many computers have an eSATA connection and eSATA cables are very short, often making access difficult.

NAS (Network Attached Storage) devices offer a tempting alternative for backing up across your network. The are general too slow, slower than USB, for large full backups.

Corbian Backup can use FTP to backup to a server across a network or the Internet. If you use ADSL, your upload speed will be too slow for a full backup to an Internet based server.

Download

Download Cobian Backup from www.educ.umu.se/~cobian/cobianbackup.htm.

Conclusion

Cobian Backup is ok for small backups. The split Zip files for use on DVDs are unreliable. Do not use split files. The default settings are too slow. Do not use the Cobian Backup default Zip or 7zip settings for large backups.