NAME
pfs, PFS — portable file system
DESCRIPTION
The Portable File System, or
PFS,
allows access to a variety of CD-ROM file systems.
Currently supported file systems include:
iso9660,
high sierra,
RockRidge Interchange.
The PFS package consists of 7 programs:
- pfs_mountd
is responsible for maintaining local and remote mounts. It must be running
on both PFS clients and PFS servers. The
pfs_mountd
program validates arguments, and spawns
pfs_mountd.rpc.
- pfs_mountd.rpc
is the RPC server code associated with
pfs_mountd.
It should not be executed directly.
- pfsd
responds to all client requests for a given mounted CD-ROM file system.
pfsd
needs to be running on all systems designated as PFS servers.
pfsd
validates arguments, and spawns
pfsd.rpc.
- pfsd.rpc
is the RPC server code associated with
pfsd.
It should not be executed directly.
- pfs_exportfs
makes local directories available for mounting by PFS clients.
- pfs_mount
mounts CD-ROM file system locally or from server.
- pfs_umount
unmounts CD-ROM file system locally or from server.
Client
file access calls are converted to
PFS
protocol requests, and are sent
to the server system over the network. The server receives the request,
performs the actual file system operation, and sends a response back to
the client.
The Portable File System operates in a stateful fashion using
remote procedure (RPC - rfc1057) calls built on top of external data
representation (XDR - rfc1014) protocol.
The
RPC
protocol provides for version and authentication parameters
to be exchanged for security over the network.
A server can grant access to a specific filesystem to certain
clients by adding an entry for that filesystem to the server's
/etc/pfs_exports
file and running
pfs_exportfs(1M).
A client gains access to that filesystem with the
pfs_mount
command.
Once the filesystem is mounted by the client, the server issues a file
handle to the client for each file (or directory) the client accesses
or creates.
If the disc is unmounted at the server, the file handles
becomes stale, and remote requests will return stale file handle messages.
A server may also be a client with respect to filesystems it
has mounted over the network, but its clients cannot gain access
to those filesystems. Instead, the client
must mount a filesystem directly from the server on which it resides.
ERRORS
Generally physical disk I/O errors detected at the server are returned
to the client for action. If the server is down or inaccessible,
the client will see the message:
PFS server host not responding, retrying...
It will retry 4 times, and then finally return failure.
AUTHOR
pfs
was developed by Young Minds, Inc.
