|aim of backup||to create single set or multiple sets of secondary copies of files||to manage multiple copies of data in such a manner that safety of each file is no less than safety as set up in configuration table and accessibility is no less than accessibility as set up in configuration table|
|target data unit definition||file defined by filename and path||file defined by checksum
Multiple instances of the same file are treated as identical from backup point of view regardless of actual name and location on the system. If fule is moved or copied it's backup copies are not affected
|safety of data||depends on design of software, seldom clearly defined and usually quite inflexible||Set up in configuration table for each section of working storage
area or even single files. System calculates how many copies are needed
to (statistically) achieve it and automatically creates copying requests
/ scripts. Types of copies are to be allocated using various storage volumes.
Personal photos from weekend trip are probably OK with safety 10^2 and combination of HDD storage with single copy on CD will be suficient. Results of development project costing thousands may need safety of 10^7 and fbm may need to store multiple copies on various types of media (some of them stored localy, some with trusted 3rd party, some in bank's vault) to achieve this.
|file management tools||either general purpose file managers (for stacks of coasters) or whatever supplier of backup system provides. Generally poor to non-existent.||All instances of all files are recorded in database. Standard and job-specific scripts, forms etc. can be easily created.|
|obsolescence of database records||Unclear, new sets of backup copies are usually created from time to time and old ones rewritten or discarded (CDs)||Reusable media rewritten as needed, ROM type media are used forever (with reliability factor lowered gradually to take into account aging of device or availability of hardware).|
|database media||Dedicated hardware or general purpose storage (most often CD or floppy disc). Various types are seldom combined.||Any type of writeable media can be used - DVD, CD, floppy, ZIPdrives,
tape drives, HDD (local or networked) sections of HDD, USB storage, web
based storage space, memory cards in digital cameras, punch cards etc. Any
writeable storage - current, future or obsolete - local or remote -
can be used by fbm.
fbm will find optimal combination to provide best result.
fm can even create printed copy "backup" of suitable data if required.
|safety and accessibility||usually ad-hoc||Both safety and accessibility can be taken into account. Backup copies on spare section of HDD are accessible instantly but they are not very safe. CD in banks's safekeeping is quite safe but it is not readily accessible. Both should be combined for important data.|
$Date: 2003/12/09 10:27:47 $