sftp locks can get stuck

[Jan Hudec]

On Wed, Jan 04, 2006 at 19:57:43 +0100, Jan Hudec wrote:
> On Wed, Jan 04, 2006 at 19:33:45 +1100, Robert Collins wrote:
> > Actually, because of the need to annotate historical data, it is not as
> > easy as I think you think it would be - arch had massive problems due to
> > that - it was only transactional for part of its operation.
> > Transactional and isolated files are really very orthogonal - look at
> > most fast, commercial grade databases for instance.
> 
> Yes. The question is, whether their requirements on storage can be satisfied
> by a network filesystem as bad as ftp or nfs.

Well, I know about one database that does not rely on inter-process
communication or special server - SQLite. So I looked what it's
documentation has to say about network filesystems. I found this:

: SQLite uses reader/writer locks to control access to the database.
: (Under Win95/98/ME which lacks support for reader/writer locks, a
: probabilistic simulation is used instead.) But use caution: this locking
: mechanism might not work correctly if the database file is kept on an
: NFS filesystem. This is because fcntl() file locking is broken on many
: NFS implementations. You should avoid putting SQLite database files on
: NFS if multiple processes might try to access the file at the same time.
: On Windows, Microsoft's documentation says that locking may not work
: under FAT filesystems if you are not running the Share.exe daemon.
: People who have a lot of experience with Windows tell me that file
: locking of network files is very buggy and is not dependable. If what
: they say is true, sharing an SQLite database between two or more Windows
: machines might cause unexpected problems.

-- 
						 Jan 'Bulb' Hudec <bulb at ucw.cz>
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