On Aug 20, 2010, at 7:55 PM, Hetz Ben Hamo wrote: ... > Hello, > I have some really bizarre behavior with AOE.
The behavior doesn't have to do with AoE so much as the use of a traditional, non-cluster filesystem from more than one host, which isn't something you can do without having things go wrong. (More comments appear below.) ... > The problem: When I change a file in 1 machine, I don't see the changes on > the other machine, same thing happens when I try to erase/rename files, copy > etc. When a host mounts a filesystem, it keeps filesystem information in RAM as well as on persistent storage. It assumes that the info in RAM is the same as the info on persistent storage so that it can avoid unnecessary I/O. In a cluster filesystem like GFS, hosts communicate with one another to let one another know when these assumptions are not valid, but with a traditional filesystem like ext2, there is no such mechanism. It's a single-host filesystem design. When you try to mount a filesystem from two hosts and they each wrongly assume, "I'm the only one mounting this filesystem," the info in their RAM does *not* match the info on persistent storage. Then you wind up with corrupt data on the persistent storage, as host A writes things that make sense only based on the info it has in RAM, even though host B has changed the persistent copy of that info! -- Ed Cashin ecas...@coraid.com ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Aoetools-discuss mailing list Aoetools-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/aoetools-discuss
