Single System Image (SSI)
A single system image
(SSI) cluster is a collection of computers that appears to be a single
system. openMosix is an SSI cluster. "Appears to
be a single system" does not just apply to the view of the user, but
also to processes and filesystems.
- User - No need to login to a specific node on the
cluster; simply start the program and openMosix will migrate the
process(es) to the appropriate computer(s).
Also, with the auto-discovery daemon, new nodes
may enter the cluster without sys admin intervention.
- Process - Since openMosix operates in kernel space,
even a process is unaware of migration to another node.
- Filesystem - Processes usually operate on
data, which is likely to reside on another node; especially in the
event of migration. The transport of data from another node or an NFS
server is not practical. Both utilize the network and if more that one
process accesses a file, data integrity can be comprimised. The
openMosix File System (oMFS) allows access to files on another node,
similar to NFS, but also includes cache, timestamp and link
consistency. But wait, there's more! Direct File System Access (DFSA),which
is layered on top of oMFS, determines if it would be more efficient to
move the data to the process or migrate the process to the data.
<- Basic Operation of openMosix
openMosix System Calls ->