linux man page for ureadahead

ureadahead(8)						      System Manager's Manual						     ureadahead(8)

NAME
       ureadahead - Read files in advance during boot

SYNOPSIS
       ureadahead [OPTIONS]...	[PACK]

DESCRIPTION
       ureadahead  (uber-readahead)  is  used  during boot to read files in advance of when they are needed such that they are already in the page
       cache, improving boot performance.

       When started without any arguments, it checks for the existance and age of the default  pack  file  /var/lib/ureadahead/pack,  and  if  not
       present	or  older  than  a  month,  will discard it and retrace the boot sequence.  The pack will then contain information about the files
       opened during boot, and the blocks that were in memory at the completion of the boot.

       If the file exists and is newer than a month old, or an alternate PACK path is given on the command-line, the files listed in the pack  are
       opened and the blocks read into the page cache using the readahead(2) system call.

       Pack files are automatically optimised for Solid-State Disks or rotational Hard Drives, depending on which you have.

OPTIONS
       --verbose
	      May  be used to report on ureadahead's operation.  In particular, this causes information about the size of the pack file to be out-
	      put when reading and a complete dump of the contents of the pack file after tracing.

       --daemon
	      Places ureadahead into the background once the pack file has been read, or once tracing has been enabled.

	      This is ignored when reading on rotational hard drives, since it's important for performance reasons not to contend with other  pro-
	      cesses for I/O.

       --force-trace
	      Discards all pack files and forces re-tracing.

       --timeout=SECONDS
	      Normally	when  tracing,	ureadahead will wait for a TERM or INT signal before concluding and generating the pack file.  This option
	      instead sets a timeout after which tracing is terminated.

       --dump Dump the contents of the pack file to standard output in a pretty format, does not trace or read the contents into memory.

       --sort=SORT
	      Used with --dump to sort the output.

	      The default is open, which is the order that the files will be opened.  path sorts by path name, disk sorts by on-disk location, and
	      size sorts by the amount of data that will be read for that file.

OTHER MOUNT POINTS
       PACK  need  not	be  the filename of a pack, instead it may be the name of a mount point (or indeed any non-file within the filesystem), in
       which case the pack for that device is read instead.  This allows ureadahead to be called in the  style	ureadahead  /usr  for  filesystems
       split across multiple devices.

       Pack files for these other devices are also stored under /var/lib/ureadahead and are named mountpoint.pack

       When tracing, these will be automatically generated.

FILES
       /var/lib/ureadahead/pack

AUTHOR
       Written by Scott James Remnant <scott@netsplit.com>

BUGS
       Report bugs at <https://launchpad.net/ubuntu/+source/ureadahead/+bugs>

COPYRIGHT
       Copyright (C) 2009 Canonical Ltd.

       This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
       LAR PURPOSE.

SEE ALSO
       readahead(2)

ureadahead							    2009-09-29							     ureadahead(8)