Best way to use zram in Fedora 21?

Karel Zak kzak at
Mon Dec 8 10:36:47 UTC 2014

On Tue, Nov 25, 2014 at 09:03:20PM +0100, Juan Orti wrote:
> Hi, I know how to manually configure the zram, but what's the best way
> to do it?
> I've seen the unit zram.service of anaconda-core, and it gets activated
> when booting with inst.zram=on, but it looks like very anaconda-centric.
> Should something like [1] be packaged and included in the distro? or
> maybe we should spin off the anaconda zram.service and do it more
> generic.
> I think this is a very interesting feature for memory constrained VMs
> and other devices.
> [1]

BTW, util-linux v2.26 (f22) is going to contain new command zramctl(8)


$ zramctl --help

 lt-zramctl [options] <device>
 lt-zramctl -r <device> [...]
 lt-zramctl [options] -f | <device> -s <size>

 -a, --algorithm lzo|lz4   compression algorithm to use
 -b, --bytes               print sizes in bytes rather than in human readable format
 -f, --find                find a free device
 -n, --noheadings          don't print headings
 -o, --output <list>       columns to use for status output
     --raw                 use raw status output format
 -r, --reset               reset all specified devices
 -s, --size <size>         device size
 -t, --streams <number>    number of compression streams

 -h, --help     display this help and exit
 -V, --version  output version information and exit

Available columns (for --output):
        NAME  zram device name
    DISKSIZE  limit on the uncompressed amount of data
        DATA  uncompressed size of stored data
       COMPR  compressed size of stored data
   ALGORITHM  the selected compression algorithm
     STREAMS  number of concurrent compress operations
  ZERO-PAGES  empty pages with no allocated memory
       TOTAL  all memory including allocator fragmentation and metadata overhead
  MOUNTPOINT  where the device is mounted

For more details see zramctl(8).

 Karel Zak  <kzak at>

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