zram-generator(5)

1ZRAM-GENERATOR.CONF(5)                                  ZRAM-GENERATOR.CONF(5)
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NAME

6       zram-generator.conf  -  Systemd  unit  generator  for zram swap devices
7       (configuration)
8

SYNOPSIS

10       /usr/lib/systemd/zram-generator.conf
11       /usr/local/lib/systemd/zram-generator.conf
12       /etc/systemd/zram-generator.conf
13       /run/systemd/zram-generator.conf
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15       /usr/lib/systemd/zram-generator.conf.d/*.conf
16       /usr/local/lib/systemd/zram-generator.conf.d/*.conf
17       /etc/systemd/zram-generator.conf.d/*.conf
18       /run/systemd/zram-generator.conf.d/*.conf
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DESCRIPTION

21       These files configure devices created by  zram-generator(8).  See  sys‐
22       temd.syntax(5) for a general description of the syntax.
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CONFIGURATION DIRECTORIES AND PRECEDENCE

25       The   default   configuration  doesn´t  specify  any  devices.  Consult
26       /usr/share/zram-generator/zram-generator.conf.example  for  an  example
27       configuration file.
28
29       When  packages  need  to  customize the configuration, they can install
30       configuration  snippets   in   /usr/lib/systemd/zram-generator.conf.d/.
31       Files  in  /etc/  are reserved for the local administrator, who may use
32       this logic to override the  configuration  files  installed  by  vendor
33       packages. The main configuration file is read before any of the config‐
34       uration directories, and has the lowest precedence; entries in  a  file
35       in  any configuration directory override entries in the single configu‐
36       ration file. Files in the *.conf.d/  configuration  subdirectories  are
37       sorted by their filename in lexicographic order, regardless of which of
38       the subdirectories they reside in. When multiple files specify the same
39       option,  for options which accept just a single value, the entry in the
40       file with the lexicographically latest name  takes  precedence.  It  is
41       recommended  to  prefix  all  filenames  in those subdirectories with a
42       two-digit number and a dash, to simplify the ordering of the files.
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44       To disable a configuration file supplied by the vendor, the recommended
45       way  is  to place a symlink to /dev/null in the configuration directory
46       in /etc/, with the same filename as the vendor configuration file.
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OPTIONS

49       Each device is configured independently in its [zramN] section, where N
50       is a nonnegative integer. Other sections are ignored.
51
52       Devices with the final size of 0 will be discarded.
53
54       ·   host-memory-limit=
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56           Sets  the upper limit on the total usable RAM (as defined by MemTo‐
57           tal in /proc/meminfo, confer proc(5)) above which the  device  will
58           not be created.
59
60           This  takes  a  nonnegative  number,  representing  that  limit  in
61           megabytes, or the literal string none, which can be used  to  over‐
62           ride a limit set earlier.
63
64           Defaults to none.
65
66           For compatibility with earlier versions, memory-limit is allowed as
67           an alias for this option. Its use is discouraged,  and  administra‐
68           tors should migrate to host-memory-limit.
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70       ·   zram-fraction=
71
72           Defines  the scaling factor of the zram device´s size with relation
73           to the total usable RAM.
74
75           This takes a nonnegative floating-point  number  representing  that
76           factor.
77
78           Defaults to 0.5.
79
80       ·   max-zram-size=
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82           Sets the limit on the zram device´s size obtained by zram-fraction.
83
84           This  takes  a  nonnegative  number,  representing  that  limit  in
85           megabytes, or the literal string none, which can be used  to  over‐
86           ride a limit set earlier.
87
88           Defaults to 4096.
89
90       ·   compression-algorithm=
91
92           Specifies the algorithm used to compress the zram device.
93
94           This takes a literal string, representing the algorithm to use.
95           Consult  /sys/block/zram0/comp_algorithm  for  a  list of currently
96           loaded compression algorithms, but note that additional ones may be
97           loaded on demand.
98
99           If  unset, none will be configured and the kernel´s default will be
100           used.
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ENVIRONMENT VARIABLES

105       Setting ZRAM_GENERATOR_ROOT during parsing will cause /proc/meminfo  to
106       be    read    from   $ZRAM_GENERATOR_ROOT/proc/meminfo   instead,   and
107       {/usr/lib,/usr/local/lib,/etc,/run}/systemd/zram-generator.conf  to  be
108       read from $ZRAM_GENERATOR_ROOT/{/usr/lib,/usr/local/lib,/etc,/run}/sys‐
109       temd/zram-generator.conf.
110

EXAMPLES

112       The default configuration will yield the following:
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116            zram device size [MB]
117                ^
118                │
119             4G>│               ooooooooooooo
120                │             o
121                │           o
122                │         o
123             2G>│       o
124                │     o
125                │   o
126           512M>│ o
127                0───────────────────────> total usable RAM [MB]
128                  ^     ^       ^
129                  1G    4G      8G
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REPORTING BUGS

134       <https://github.com/systemd/zram-generator/issues>
135