ref: 762e98d47e8d812f0dbe4b64ef2a73357bdebeee
dir: /sys/man/4/cfs/
.TH CFS 4 .SH NAME cfs \- cache file system .SH SYNOPSIS .B cfs .B -s .RB [ -dknrS ] .RB [ -f .IR partition ] .PP .B cfs .B -a .I netaddr .RB [ -dknrS ] .RB [ -f .IR partition ] .RI [ mtpt ] .PP .B cfs .B -F .I srvfile .RB [ -dknrS ] .RB [ -f .IR partition ] .RI [ mtpt ] .SH DESCRIPTION .I 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. .I 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 .I cfs checks the consistency of cached information and discards any old information for that file. .PP .I Cfs mounts onto .I mtpt (default .BR /mnt/cfs ) after connecting to the file server. .PP The options are: .TF - .PD .TP .BI "a " netaddr dial the destination .I netaddr to connect to a remote file server. Exclusive with .BR -F . .TP .B d turn on debugging. .TP .BI "f " partition use file .I partition as the cache disk partition. .TP .BI "F " srvfile open .I srvfile (often a file under .BR /srv ) to connect to a remote file server. Exclusive with .BR -a . .TP .B k keep cache contents even if they might have come from a different server. .I Cfs will obey .B -r even if .B -k is given. .TP .B n mount the remote file server without authentication; often useful with .BR -F . .TP .B r reformat the cache disk partition. .TP .B s the connection to the remote file server is on file descriptors 0 and 1. .TP .B S turn on statistics gathering. A file called .B 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. .PP All 9P messages except .BR read , .BR clone , and .B walk (see .IR intro (5)) are passed through .I cfs unchanged to the remote server. If possible, a .B read is satisfied by cached data. Otherwise, the file server is queried for any missing data. .SH FILES .TP .B /dev/sdC0/cache Default file used for storing cached data. .SH SOURCE .B /sys/src/cmd/cfs