Re: How to use zram ?

[Pierre Couderc <pierre@couderc.eu>]

On 09/28/2017 11:56 AM, tomas@tuxteam.de wrote:
> On Thu, Sep 28, 2017 at 11:47:56AM +0200, Pierre Couderc wrote:
> > I have found no howto for zram under debian,  nor even the word
> > "zram" in the archives of this list !
> >
> > I have tried to use zramctl but it refuses with :
> >
> > root@nous:~# zramctl --find --size 1024M
> > zramctl: no free zram device found
> >
> > I suppose I should init something somewere, but what ?
> >
> > On the contrary ubuntu has a dedicated zram-config to make the job.
> >
> > Thanks for any help.
> I didn't even know what it is -- but the zram(8) man page and a little
> guesswork at least leads in some direction.
>
> I assume you'd want to load the zram kernel module (sudo modprobe zram,
> I'd guess) to be in in the fun.
>
> There's some doc about the Linux kernel module itself (just follow the
> link in the above man page).
>
> Let us know how it works out and... make a backup first!
Thank you very much. I have not found "the zram(8) man page "... But It 
seems to work :

root@nous:~# modprobe zram num_devices=2
root@nous:~# zramctl --find --size 1024M
/dev/zram0
root@nous:~# zramctl --find --size 1024M
/dev/zram1
root@nous:~# free -th
              total        used        free      shared buff/cache   
available
Mem:           3.8G         73M        3.6G        5.5M 146M        3.5G
Swap:            0B          0B          0B
Total:         3.8G         73M        3.6G
root@nous:~# mkswap /dev/zram0
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=66e3aa01-a4b8-4308-b317-608c6a072810
root@nous:~# free -th
              total        used        free      shared buff/cache   
available
Mem:           3.8G         73M        3.6G        5.5M 146M        3.5G
Swap:            0B          0B          0B
Total:         3.8G         73M        3.6G
root@nous:~# swapon /dev/zram0
root@nous:~# free -th
              total        used        free      shared buff/cache   
available
Mem:           3.8G         73M        3.6G        5.5M 147M        3.5G
Swap:          1.0G          0B        1.0G
Total:         4.8G         73M        4.6G
root@nous:~# mkswap /dev/zram1
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=69b8070b-3b8d-4234-a773-a59812e54552
root@nous:~# swapon /dev/zram1
root@nous:~# free -th
              total        used        free      shared buff/cache   
available
Mem:           3.8G         74M        3.6G        5.5M 147M        3.5G
Swap:          2.0G          0B        2.0G
Total:         5.8G         74M        5.6G
root@nous:~#

Now I suppose I shouls put that in a systemd script...

Thank you very much.

PC