Recently I started an open source project "cutils" on the sourceforge: http://sourceforge.net/projects/crablfs/
The document can be found at: http://crablfs.sourceforge.net/#ru_data_man This project's mirrord/fs_mirror tool is a near realtime file system mirroring application across 2 or more hosts, something like MySQL's replication, but it's for the file system especially with a great amountof small files, such as the php scripts and images of a website or the (vitual) websites. There are several ways to use this tool. The simplest is to mirror a host's file system to another host for backup, and use the rotate function(in the future version) or rotate scripts to get a daily or hourly snapshot with the hard link. Or futhur more, you can use it this way: This graph should be displayed with monospaced fonts: +----------+ | worker | -[mirrord] -----------\ +----------+ | ...... | | +----------+ | | worker | -[mirrord] -----------\ +----------+ | V [fs_mirror] | +----------+ +----------+ | worker | -[mirrord] ---> | backup | +----------+ +----------+ | | [take_over] | | | V | +----------+ | | rescue | <------------------- NFS +----------+ This is the multi to one backup, which is cost efficient. If one of the worker hosts fails, you can subsitute the failed worker with the rescue host, with the aid of any high available method, such as heartbeat project. By this way, you can use 1 or 2 hosts to support the HA of more than 3 servers. Or you can also use it as an IDS(Intrusion Detection System) like a realtime "tripware", or you can make a mirror chain that a host B mirrors from A and be mirrored by C, etc ... I will also try to research a way to use it as a distributed implemetation with one write and multi-read model. mirrord/fs_mirror makes use of inotify, which is a function afforded by the recent Linux (from 2.6.12). It is a counterpart of FAM, since Linux FAM has stopped so long. Now it works for me, on a RHEL4 system and the LFS 6.2, I hope this tool can be useful to you too. Thanks. -- http://mail.python.org/mailman/listinfo/python-list
