diff options
| author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2013-11-13 00:42:22 -0500 |
|---|---|---|
| committer | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2014-01-11 16:54:59 -0500 |
| commit | 348ced909724a1331b85d57aede80a102a00e428 (patch) | |
| tree | 1b58129221dcfee9d8e2679cf48f12882f565bc2 /man | |
| parent | b94801803417c23d099cb7e508754181ecd27f9c (diff) | |
journald: do not free space when disk space runs low
Before, journald would remove journal files until both MaxUse= and
KeepFree= settings would be satisfied. The first one depends (if set
automatically) on the size of the file system and is constant. But
the second one depends on current use of the file system, and a spike
in disk usage would cause journald to delete journal files, trying to
reach usage which would leave 15% of the disk free. This behaviour is
surprising for the user who doesn't expect his logs to be purged when
disk usage goes above 85%, which on a large disk could be some
gigabytes from being full. In addition attempting to keep 15% free
provides an attack vector where filling the disk sufficiently disposes
of almost all logs.
Instead, obey KeepFree= only as a limit on adding additional files.
When replacing old files with new, ignore KeepFree=. This means that
if journal disk usage reached some high point that at some later point
start to violate the KeepFree= constraint, journald will not add files
to go above this point, but it will stay (slightly) below it. When
journald is restarted, it forgets the previous maximum usage value,
and sets the limit based on the current usage, so if disk remains to
be filled, journald might use one journal-file-size less on each
restart, if restarts happen just after rotation. This seems like a
reasonable compromise between implementation complexity and robustness.
Diffstat (limited to 'man')
| -rw-r--r-- | man/journald.conf.xml | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/man/journald.conf.xml b/man/journald.conf.xml index b362c5de2c..e0796e1cce 100644 --- a/man/journald.conf.xml +++ b/man/journald.conf.xml @@ -250,20 +250,35 @@ <para><varname>SystemMaxUse=</varname> and <varname>RuntimeMaxUse=</varname> control how much disk space the - journal may use up at - maximum. Defaults to 10% of the size - of the respective file - system. <varname>SystemKeepFree=</varname> - and + journal may use up at maximum. + <varname>SystemKeepFree=</varname> and <varname>RuntimeKeepFree=</varname> control how much disk space - systemd-journald shall always leave - free for other uses. Defaults to 15% - of the size of the respective file - system. systemd-journald will respect - both limits, i.e. use the smaller of - the two values. - <varname>SystemMaxFileSize=</varname> + systemd-journald shall leave free for + other uses. + <command>systemd-journald</command> + will respect both limits and use the + smaller of the two values.</para> + + <para>The first pair defaults to 10% + and the second to 15% of the size of + the respective file system. If the + file system is nearly full and either + <varname>SystemKeepFree=</varname> or + <varname>RuntimeKeepFree=</varname> is + violated when systemd-journald is + started, the value will be raised to + percentage that is actually free. This + means that if before there was enough + free space and journal files were + created, and subsequently something + else causes the file system to fill + up, journald will stop using more + space, but it'll will not removing + existing files to go reduce footprint + either.</para> + + <para><varname>SystemMaxFileSize=</varname> and <varname>RuntimeMaxFileSize=</varname> control how large individual journal |