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:
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.

Default file used for storing cached data.

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