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MFS File System
Given that you have enabled MFS in the kernel configuration and in the /etc/default/mosix file, and that you have started Mosix, you can now mount thee MFS file system. In the case of the machines in the Ralphzilla cluster, I created a directory /mfs to serve as the mount point on each of the cluster machines. The file system can then be mounted to that mount point with the command "mount -t mfs /mfs". Once you've done that, the complete file system for each of the cluster machines is exposed under the directory structure /mfs/x where x is the mosix number of the machine in question. As a result, any given location on the filesystem of any machine can be accessed by any machine in the cluster through a consistent path. For example, the /data directory on Ralphzilla-raider, AKA Mosix #4, is consistently available as /mfs/4/data within the cluster. Indeed, it is possible to read any of the files on any of the systems in the cluster through the samba share on Ralphzilla. As I've shared the root ("/") filesystem, any directory on any machine is available through /mfs on that share. Access to the files is, of course, constrained by user rights within the directory in question on the specific machine on which the directory resides.
MFS is extremely fast for a network file system, largely because it operates at a lower level within the kernel than do other network file systems. Benchmarks completed by the Mosix development team suggest data transfer rates for Mosix with the DFSA option enabled to be in the neighborhood of 150% of transfer rates for NFS. (These benchmarks, and other information on MFS, can be found in the paper "The MOSIX Scalable Cluster File Systems for LINUX" in the publications section of the Mosix web site.) Anecdotally, I can attest to that. At one point during the setup of Ralphzilla I had cause to move a file containing a Postgresql database backup of perhaps 400 Mb. from a machine external to the cluster where it resided on a slow IDE drive to the /data directory of Ralphzilla-raider. Rather than moving the file in two jumps, I ftp'd to the source machine from Ralphzilla and specified tbe destination of the retrieved file as /mfs/4/data/(filename). That transfer, from a slow IDE drive through two shared 10 Mbps shared hubs, sustained throughput in the neighborhood of 560-580 Kbps, albeit with relatively little other network traffic with which to contend for the shared medium. Use of MFS is highly-recommended.
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