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# 19.4. File Systems

19.4.1. What's oMFS, how do I use, and where do I get it?:
19.4.2. Can somebody explain to me the difference bewteen MFS and DFSA, and why I would need DFSA?:

19.4.1. What's oMFS, how do I use, and where do I get it?:

The openMosix File System (oMFS) is the filesystem used by openMosix kernels. You get it by installing an openMosix kernel on the nodes of your cluster with oMFS enabled in the kernel-config. (It should be enabled in the openMosix RPMs by default.)

You should also enable Direct Filesystem Access (DFSA) which allows a migrated process to execute many syscalls on the remote node locally without the need to migrate it back to its home node.

The use and administration of oMFS is very similar to NFS, but unlike NFS, oMFS features:

- Cache consistency

- Timestamp consistency

- Link consistency

The DFSA layer on top of oMFS makes sure to move the process to the data, instead of vice versa, whenever it makes sense.

Please read more about oMFS and how to use it in earlier chapters of the HOWTO.

19.4.2. Can somebody explain to me the difference bewteen MFS and DFSA, and why I would need DFSA?:

DFSA stands for Direct File System Access and is an optimization. It allows remote proccesses to perform some file system system calls locally rather then sending them to their home node. MFS stands for Mosix File System and allows all nodes access to all node filesystems. DFSA runs on top of a cluster filesystem, in this case MFS.

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