x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SYSTEMD-READAHEAD-REPLAsystemd-readahead-reSYSTEMD-READAHEAD-REPLAY.SERVICE(8)
NAME
systemd-readahead-replay.service, systemd-readahead-collect.service,
systemd-readahead-done.service, systemd-readahead-done.timer, systemd-
readahead - Disk read ahead logic
SYNOPSIS
systemd-readahead-replay.service
systemd-readahead-collect.service
systemd-readahead-done.service
systemd-readahead-done.timer
/usr/lib/systemd/systemd-readahead/systemd-readahead [OPTIONS...]
COMMAND
[DIRECTORY | FILE]
DESCRIPTION
systemd-readahead-collect.service is a service that collects disk usage
patterns at boot time. systemd-readahead-replay.service is a service
that replays this access data collected at the subsequent boot. Since
disks tend to be magnitudes slower than RAM, this is intended to
improve boot speeds by pre-loading early at boot all data on disk that
is known to be read for the complete boot process.
systemd-readahead-done.service is executed a short while after boot
completed and signals systemd-readahead-collect.service to end data
collection. On this signal, this service will then sort the collected
disk accesses and store information about them in /.readahead.
Normally, both systemd-readahead-collect.service and
systemd-readahead-replay.service are activated at boot so that access
patterns from the preceding boot are replayed and new data collected
for the subsequent boot. However, on read-only media where the
collected data cannot be stored, it might be a good idea to disable
systemd-readahead-collect.service.
On rotating media, when replaying disk accesses at early boot,
systemd-readahead-replay.service will order read requests by their
location on disk. On non-rotating media, they will be ordered by their
original access timestamp. If the file system supports it,
systemd-readahead-collect.service will also defragment and rearrange
files on disk to optimize subsequent boot times.
OPTIONS
systemd-readahead understands the following options:
--files-max=
Maximum number of files to read ahead. Only valid for thes collect
command.
--file-size-max=
Maximum size of files in bytes to read ahead. Only valid for the
collect and replay commands.
--timeout=
Maximum time in microseconds to spend collecting data. Only valid
for the collect command.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
COMMANDS
The following commands are understood by systemd-readahead:
collect [DIRECTORY]
Collect read-ahead data on early boot. When terminating, it will
write out a pack file to the indicated directory containing the
read-ahead data.
replay [DIRECTORY]
Perform read-ahead on the specified directory tree.
analyze [FILE]
Dumps the content of the read-ahead pack file to the terminal. For
each file, the output lists approximately how much will be read
ahead by the replay command.
SEE ALSO
systemd(1)
systemd 210 SYSTEMD-READAHEAD-REPLAY.SERVICE(8)
Want to link to this manual page? Use this URL:
<http://star2.abcm.com/cgi-bin/bsdi-man?query=systemd-readahead-replay.service&sektion=8&manpath=>