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

       ureadahead - Read files in advance during boot

       ureadahead [OPTIONS]...  [PACK]

       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  rota-
       tional Hard Drives, depending on which you have.

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

              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
              processes for I/O.

              Discards all pack files and forces re-tracing.

              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.

              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 loca-
              tion, and size sorts by the amount of data that will be read for
              that file.

       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/ure-
       adahead and are named mountpoint.pack

       When tracing, these will be automatically generated.


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

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

       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 PARTICULAR


ureadahead                        2009-09-29                     ureadahead(8)
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