*special, const char *directory,
tmpfsis a memory based file system which uses kernel resources relating to the VM system and page cache as a file system. Once mounted, a
tmpfsfile system provides standard file operations and semantics.
tmpfsis so named because files and directories are not preserved across reboot or unmounts, all files residing on a
tmpfsfile system that is unmounted will be lost.
tmpfs file systems can be mounted with the
mount -F tmpfs swap directory
Alternatively, to mount a
system on /tmp at multi-user startup time
(maximizing possible performance improvements), add the following line to
swap −/tmp tmpfs − yes −
tmpfs is designed as a performance
enhancement which is achieved by caching the writes to files residing on a
tmpfs file system. Performance improvements are most
noticeable when a large number of short lived files are written and accessed
tmpfs file system. Large compilations with
tmpfs mounted on /tmp are a
good example of this.
tmpfs should be aware of some
constraints involved in mounting a
system. The resources used by
tmpfs are the same as
those used when commands are executed (for example, swap space allocation).
This means that large sized
tmpfs files can affect
the amount of space left over for programs to execute. Likewise, programs
requiring large amounts of memory use up the space available to
tmpfs Users running into this constraint (for
example, running out of space on
tmpfs) can allocate
more swap space by using the swap(1M)
Another constraint is that the number of files available in a
tmpfs file system is calculated based on the
physical memory of the machine and not the size of the swap
device/partition. If you have too many files,
will print a warning message and you will be unable to create new files. You
cannot increase this limit by adding swap space.
Normal file system writes are scheduled to be written to a
permanent storage medium along with all control information associated with
the file (for example, modification time, file permissions).
tmpfs control information resides only in memory and
never needs to be written to permanent storage. File data remains in core
until memory demands are sufficient to cause pages associated with
tmpfs to be reused at which time they are copied out
An additional mount option can be specified to control the size of
tmpfs file system. See
mount_tmpfs(1M) for more
tmpfsruns out of space, one of the following messages will display in the console.
tmpfsis attempting to write more than it is allowed, or if currently executing programs are using a lot of memory. To make more space available, remove unnecessary files, exit from some programs, or allocate more swap space using swap(1M).
tmpfsran out of physical memory while attempting to create a new file or directory. Remove unnecessary files or directories or install more physical memory.
tmpfsfile system are not preserved across reboots or unmounts. Command scripts or programs which count on this will not work as expected.
TMPDIR to/tmp. Compilers use the value in this environment variable as the name of the directory to store intermediate files.
swap to a
tmpfs file is
df(1M) output is of limited
accuracy since a
tmpfs file system size is not
static and the space available to
tmpfs is dependent
on the swap space demands of the entire system.
|October 9, 1990||OmniOS|