MIZZI Computer Software GmbH

BACKFS/filer Disk to Disk backup with History

 		 







BACKFS is a flexible, easy-to-use backup utility designed to backup and restore data files on a file by file basis. It provides simple copy of a file system, a full backup copy, and an incremental backup strategy and is designed to backup large volumes as well as small directories of only a few hundred files. Therefore it is useful not only for professionals user, BACKFS is nevertheless a perfect solution for small home offices too.



Introduction



There are several backup methods used today. One of these is the backup to tape. This operation seems sufficient but during the last 10 years problems appeared with the backup to tape. Disk storage was growing much more than the capacity of the tapes. 30 years ago a single big reel tape (130 MB) has stored the content of a single disk (100 MB). These days  a single tape can store about 200 GB but standard disks configured as a RAID set have a size up to 5 TB on a single file system. This requires about 25 tapes to store the content of  a single RAID set. Concerning the  backup time it is getting worse. 30 years ago 10-15 min were necessary to write one tape today one needs 2.5 hours per tape. This leads to backup times of 50 hours for a single full backup and a tape library is needed in any case. Incremental backup is not such a big problem due to the fact that the number of files which has been changed every day has not been increased in the same order as the size of the disk systems. Also if the backup seems to be possible the restoration of a disk or RAID set seems to be not. If your /home directory crashes the restoration of that disk with a tape library will need 50-100 hours. This is not acceptable in most cases.

What about solutions? Many administrators think that two copies of the same disk should be the best solutions and are using a mirror (RAID1) set. These copies are usually located in two different buildings (to avoid data loss due to fire) and use a simple block copy instead of a file copy. It seems the basic problem is solved, but others are still present! Firstly, there is no backup in case of a file system crash due to software errors because the copied file system will crash also and secondly there is no version control. This means that the user can not retrieve any version of a file which was saved during the last backups. Due to this reasons, a backup to tape is additionally necessary. 

All these problems have been driving the development of BACKFS. This utility will create an image of a disk on a file by file basis. BACKFS can spread files over different type of file system and provides version control. In case of a disk crash the backup copy can be mounted immediately and your last backup is available after a few minutes. BACKFS is also much faster than any other incremental backup. Compared to other tape backup utilities, BACKFS is sometimes 20 times faster. Therefore, it is possible to perform an incremental backup many times a day. Our test machine contains a file system with 250000 files and 10 GB data. This file system can be backed up (incrementally) to a NFS-mounted file system within 20 seconds.

At this time you may think all of that I can do without BACKFS, but other tools provide part of the functionality, but none comprise all of them.

tar fails to do incremental copies at all (new and old style).
cpio does not delete files.
dump/restore does not delete files too.

All of them do not detect moved directories and none can move overwritten files to version directories (version control). If the source disk crash while being backed up, the file which is currently copied is lost. If you want to have only all files copied rather than an image of your disk use one of the above programs and wait for the first crash .....
You might think BACKFS is necessary for enterprise computing only, but BACKFS is the ideal backup for your home machine too. If you own a second disk or an external USB Disk you can backup your main disk within of 20 seconds. No burning of CD's or DVD's is required and full version control is available too. Just call BACKFS before you shutdown your PC!


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