Availl has introduced its wide area file system, Availl 3.0, using replication and mirroring techniques with real-time file locking. Files are still stored in local offices but synchronised with a master copy in a data centre. Whenever a file is updated the byte-level changes are sent to the data centre and then mirrored out to the other remote offices holding copies.

Typically a wide area file system or WAFS product transmits entire files to branch offices whenever a user tries to access a centrally stored file. These files are compressed and then network optimisation techniques are used to reduce the IP packet processing burden. The file arrives faster in the remote office and there it is stored in cache for other users to access at local access speed. This is the premise of Brocade/Tacit/Microsoft, Riverbed, Expand Networks,and Cisco WAFS products.

Availl claims that its mirroring transfer method 'vastly decreases (the) bandwidth' needed for file transfer 'by 95 percent and more.' Customers can have all the security and enhanced administration efficiency of centrally-held files without sacrificing any access speed by local users in branch offices. The product runs on existing Windows servers with no change to the Windows file structure.

From a user's point of view all files are fully mirrored to the local drive as they change anywhere.

File state is maintained so that multiple users in different offices, perhaps around the globe, cannot open the same file for simultaneous write access. A changed file is virtually instantly updated at all the locations holding copies. Avail says a million or more files can be present in its system and distances can range from campus through metro to international scale.

William Ip, the CIO of Wardrop Engineering, an engineering firm with ten offices around the globe, said: "Solutions that depend only on WAN optimisation and compression simply break down over long distances. It is real-time file locking and local disk speeds that allowed us to create truly distributed project teams around the globe."

Availl 3.0 is available now and priced starting at $1,495 (about £830).