On Fri, 17 Oct 2008, Jerry Tan wrote: > We are always the company who believe "The Network is the computer".
Excellent! > Gamin is File Alteration Monitor. you can refer to > http://www.gnome.org/~veillard/gamin/overview.html for more > information. it depends one kernel module called File Event > Notification (FEN) on solaris . So when File is > added/moved/modified, FEN will notify gamin, gamin will notify its > registerd applications such as tracker. then tracker will know that > some file need to be reindexed. As a minor clarification/correction the FEN service can only notify about a file added/moved/modified if the local kernel is aware of it. If a process on the local system made the change, or the local kernel made the change since it is acting as a NFS/SMB server, then it is possible to notify. If the file is accessed remotely via NFS/SMB and resides on some other server, then one of the thousand other computers with the ability to update the file can do so without producing any notification to this particular kernel. In order to detect the actual changes, an equivalent to 'find' needs to be executed periodically. Most of us are aware what happens to networks and servers when users run several recursive 'find' tasks. > Tracker does not care this file comes from NFS share directory or > local file directory, as long as it can read this file. I think that it does make a difference. Besides worrying about impact to the network, I worry about performance impact to the local computer. High bandwidth changes to the local filesystem can cause a huge volume of notifications and quite a lot of subsequent trackerd activity. This is exactly the problem I see under Mac OS-X where the 'mdworker' process takes 1/2 the available resources on a two CPU system when the user is doing a simple recursive file copy. As a result, the file copy goes much slower than it would without the competing overhead. This turns a high performance system into a low performance system. Home directories of the future are likely to contain a terrabyte or more data. In some situations, the user keeps most data in their home directory. It is important that the OS and desktop not cause performance problems due to huge amounts of data in a home directory. Bob ====================================== Bob Friesenhahn bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
