cfs - cache file system cfs -s [ -dknrS ] [ -f partition ]

cfs -a netaddr [ -dknrS ] [ -f partition ] [ mtpt ]

cfs -F srvfile [ -dknrS ] [ -f partition ] [ mtpt ]

Cfs is a user-level file server that caches data from remote files onto a local disk. It is normally started by the kernel at boot time, though users may start it manually. Cfs is interposed between the kernel and a network connection to a remote file server to improve the efficiency of access across slow network connections such as modem lines. On each open of a file cfs checks the consistency of cached information and discards any old information for that file.

Cfs mounts onto mtpt (default / ) after connecting to the file server.

The options are: .TF -

"a " netaddr dial the destination netaddr to connect to a remote file server. Exclusive with -F .

d turn on debugging.

"f " partition use file partition as the cache disk partition.

"F " srvfile open srvfile (often a file under /srv ) to connect to a remote file server. Exclusive with -a .

k keep cache contents even if they might have come from a different server. Cfs will obey -r even if -k is given.

n mount the remote file server without authentication; often useful with -F .

r reformat the cache disk partition.

s the connection to the remote file server is on file descriptors 0 and 1.

S turn on statistics gathering. A file called cfsctl at the root of the caching file system can be read to get statistics concerning number of calls/bytes on client and server sides and latencies.

All 9P messages except read , clone , and walk (see intro (5)) are passed through cfs unchanged to the remote server. If possible, a read is satisfied by cached data. Otherwise, the file server is queried for any missing data.

/dev/sdC0/cache Default file used for storing cached data.

/sys/src/cmd/cfs