CFS(4)CFS(4)
NAME
cfs – cache file system
SYNOPSIS
cfs
-s
[-dknrS]
[-f
partition]
cfs
-a
netaddr
[-dknrS]
[-f
partition]
[mtpt]
cfs
-F
srvfile
[-dknrS]
[-f
partition]
[mtpt]
DESCRIPTION
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
/mnt/cfs)
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.
FILES
/dev/sdC0/cache
Default file used for storing cached data.
SOURCE
/sys/src/cmd/cfs