# zramctl - set up and control zram devices - man(8) - [phpMan]

[_ZRAMCTL_(8)](https://www.chedong.com/phpMan.php/man/ZRAMCTL/8/markdown)                              System Administration                             [_ZRAMCTL_(8)](https://www.chedong.com/phpMan.php/man/ZRAMCTL/8/markdown)

## NAME
       zramctl - set up and control zram devices

## SYNOPSIS
       Get info:
           **zramctl **[options]

       Reset zram:
           **zramctl -r _**zramdev_...

       Print name of first unused zram device:
           **zramctl -f**

       Set up a zram device:
           **zramctl **[**-f **| _zramdev_] [**-s _**size_] [**-t _**number_] [**-a _**algorithm_]

## DESCRIPTION
       **zramctl **is used to quickly set up zram device parameters, to reset zram devices, and to query
       the status of used zram devices.

       If no option is given, all non-zero size zram devices are shown.

       Note that _zramdev_ node specified on command line has to already exist. The command **zramctl**
       creates a new _/dev/zram<N>_ nodes only when **--find **option specified. It’s possible (and
       common) that after system boot _/dev/zram<N>_ nodes are not created yet.

## OPTIONS
### -a --algorithm lzo
           Set the compression algorithm to be used for compressing data in the zram device.

           The **list of supported algorithms could be inaccurate **as it depends on the current kernel
           configuration. A basic overview can be obtained by using the command "cat
           /sys/block/zram0/comp_algorithm"; however, please note that this list might also be
           incomplete. This is due to the fact that ZRAM utilizes the Crypto API, and if certain
           algorithms were built as modules, it becomes impossible to enumerate all of them.

### -f --find
           Find the first unused zram device. If a **--size **argument is present, then initialize the
           device.

### -n --noheadings
           Do not print a header line in status output.

### -o --output _
           Define the status output columns to be used. If no output arrangement is specified, then
           a default set is used. Use **--help **to get a list of all supported columns.

### --output-all
           Output all available columns.

### --raw
           Use the raw format for status output.

### -r --reset
           Reset the options of the specified zram device(s). Zram device settings can be changed
           only after a reset.

### -s --size _
           Create a zram device of the specified _size_. Zram devices are aligned to memory pages;
           when the requested _size_ is not a multiple of the page size, it will be rounded up to the
           next multiple. When not otherwise specified, the unit of the _size_ parameter is bytes.

           The _size_ argument may be followed by the multiplicative suffixes KiB (=1024), MiB
           (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g.,
           "K" has the same meaning as "KiB") or the suffixes KB (=1000), MB (=1000*1000), and so on
           for GB, TB, PB, EB, ZB and YB.

### -t --streams _
           Set the maximum number of compression streams that can be used for the device. The
           default is use all CPUs and one stream for kernels older than 4.6.

### -h --help
           Display help text and exit.

### -V --version
           Print version and exit.

## EXIT STATUS
       **zramctl **returns 0 on success, nonzero on failure.

## FILES
       _/dev/zram[0..N]_
           zram block devices

## EXAMPLE
       The following commands set up a zram device with a size of one gigabyte and use it as swap
       device.

            # zramctl --find --size 1024M
            /dev/zram0
            # mkswap /dev/zram0
            # swapon /dev/zram0
            ...
            # swapoff /dev/zram0
            # zramctl --reset /dev/zram0

## AUTHORS
       Timofey Titovets <<nefelim4ag@gmail.com>>, Karel Zak <<kzak@redhat.com>>

## SEE ALSO
       Linux kernel documentation <<https://docs.kernel.org/admin-guide/blockdev/zram.html>>

## REPORTING BUGS
       For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.

## AVAILABILITY
       The **zramctl **command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <<https://www.kernel.org/pub/linux/utils/util-linux/>>.

util-linux 2.39.3                            2023-11-21                                   [_ZRAMCTL_(8)](https://www.chedong.com/phpMan.php/man/ZRAMCTL/8/markdown)