CFS(4)CFS(4)NAMEcfs - cache file system
SYNOPSIScfs-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 ker‐
nel 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:
dial the destination netaddr to connect to a remote file server.
Exclusive with -F.
d turn on debugging.
use file partition as the cache disk partition.
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 differ‐
ent server. Cfs will obey -r even if -k is given.
n mount the remote file server without authentication; often use‐
ful 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 con‐
cerning number of calls/bytes on client and server sides and
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.
Default file used for storing cached data.