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File synchronization

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File synchronization (or 'syncing') in computing is the process of making sure that files in two or more locations are updated through certain rules.[citation needed]

In one-way synchronization, also called mirroring, updates files are copied only from a 'source' location to a 'target' location, or locations, but no files are copied back to the source location. In two-way sync, updated files are copied in both directions, usually with the purpose of keeping the two locations identical to each other. The term synchronization is used in this article to mean exclusively two-way file synchronization.[citation needed]

File synchronization is commonly used for home backups on external hard drives or updating for transport on USB flash drives. The automatic process prevents copying already identical files and thus can save considerable time from a manual copy, also being faster and less error prone.[1] However this suffers from the limitation that the synchronized files have to physically fit in the portable drive. Synchronization software that only keeps a list of files and the changed files circumvents this problem (E.g. the "snapshot" feature in Beyond Compare or the "package" feature in Synchronize It!). It is particularly useful for mobile workers, or others that work on multiple computers. It is possible to synchronize multiple locations by synchronizing them a pair at a time.

Common features

  • Encryption for security, particularly when synchronizing across the Internet.
  • Compressing any data sent across a network, this requires a server.
  • Conflict detection where a file has been modified on both sources, as opposed to where it has only been modified on one. No conflict detection can lead to overwriting copies of the file with the most recent version causing data loss. For conflict detection, the synchronization software needs to keep a database of the synchronized files.
  • Specific support for using an intermediate storage device, such as a removable flash disc, to synchronize two machines. Although most synchronizing programs can be used in this way, providing specific support for this can reduce the amount of data stored on the device.
  • The ability to preview any changes before they are made.
  • The ability to view differences in individual files.

Software

This is a list of notable file synchronization software.

Open source

A comparison of free and open source file synchronization software.

Name Protocol Programing Language Platforms License Version Conflict detection
Conduit (generic framework) Many Python Linux, Unix GPL
DirSync Pro file system Java Windows, Linux, Mac OS X GPL 1.02 [22-Feb-2009] No
JFileSync file system Java Windows, Linux, OS X, other Unix GPL 2.2 [20-Jul-2007] Yes
Replicator file system Basic Windows 3.5.6 [19-Nov-2008]
Unison similar to rsync; uses SSH (or file system) as transport OCaml Windows, Linux, OS X, other Unix GPL 2.27.57 [20-Jan-2008] Yes (centralized database)
Toucan Backup [2] file system C++ Windows 2000/XP/Vista/7, Wine GPL 2009-07-05 [3] No

Commercial

A comparison of proprietary software released as commercial.

Name Windows Mac Linux Other OS Open source Online backup service Freeware version Paid version Conflict detection
Allway Sync Yes No No No No Yes Yes Yes
Dmailer Sync Yes No No No No Yes No Yes
Dropbox Yes Yes Yes No No Yes Yes Yes Yes
Get Backup No Yes No No No No Yes Yes
GoodSync Yes No No No No Yes Yes Yes
Handy Backup Yes No No No No No Yes No
PowerFolder Yes Yes Yes No No Yes Yes Yes
Robocopy Yes No No No No No Yes Yes [Windows 2003] No
SpiderOak Yes Yes Yes No Partial Yes Yes Yes
SugarSync Yes Yes No iPhone, BlackBerry
Windows Mobile		 No Yes Yes Yes
SuperFlexible Yes Yes No No No Yes No Yes Yes
SyncBack Yes No No No No No Yes Yes Yes
Synchronize It! Yes No No No No No No Yes No
SyncMate No Yes No No No No No Yes
Syncplicity Yes No No No No Yes Yes Yes Yes
Ubuntu One No No Yes No Partial Yes Yes Yes

Freeware

This is a list of proprietary software released as freeware or gratis.

See also

References

  • Kerner, Sean (2008-02-13). "Get In Sync with File Syncing Software". Tom's Guide. Retrieved 2009-07-01.
  • Kerner, Sean (2008-02-27). "Syncing Software Redux: More Options". Tom's Guide. Retrieved 2009-07-01.
  1. ^ A. Tridgell (February 1999). "Efficient algorithms for sorting and synchronization" (PDF). PhD thesis. The Australian National University. {{cite journal}}: Cite journal requires |journal= (help)
  2. ^ Ilascu, Ionut (2008-05-24). "Windows software reviews; Toucan Sync, Backup and Encrypt". Softpedia. {{cite web}}: |access-date= requires |url= (help); Missing or empty |url= (help); Text "http://www.softpedia.com/reviews/windows/Toucan--Review-86404.shtml" ignored (help)
  3. ^ Lamerton, Steve (2009-07-05). "Toucan page". PortableApps. {{cite web}}: |access-date= requires |url= (help); Missing or empty |url= (help); Text "http://portableapps.com/apps/utilities/toucan" ignored (help)
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