[zfs-discuss] ZFS eating up all 16 GB RAM when combining 4k blocksize ZVOL with XFS

Bzzzz lazyvirus at gmx.com
Tue Nov 13 09:08:30 EST 2018

On Tue, 13 Nov 2018 14:38:13 +0100
Omar Siam via zfs-discuss <zfs-discuss at list.zfsonlinux.org> wrote:

> All the tasks that have a number in RSS, which I think is the actual
> RAM used, can be summed up to about 200 MB of RAM. So this is nowhere
> near the 15.1 GB that is used at that time.

A 'ps aux' also returns the VSZ (shared memory) which won't help a lot,
as it is… shared, but at least it show you which processes are requesting
the most of it.

> Sorry but I doubt the ps auxf is a suitable tool. As far as I know it 
> will show nearly the same data that crash'es ps does. I'll give it a
> try when I try 0.7.11 dkms.

You can also try with:
check /var/log/messages (& daemon.log),
dmesg | grep -i oom
top (with a low delay to see which processes are the most active.)
I just find a script that might help, launch it from the command line
in an infinite loop and redirect the output to a file:

it is interesting 'cos i.e.: I have 3 firefox open windows showing 10
processes running, each showing an unreasonable amount of either
RSS and VSZ (~3.5GB RAM total), but the script shows a _very_
different reality.

here's an output example:

COMMAND                 %MEM    SIZE
firefox                 12.2    971.36MB
vlc                     8.4     667.52MB
Suricata-Main           3.2     258.96MB
Xorg                    2.2     176.39MB
claws-mail              1.5     118.75MB
pulseaudio              1.2     101.88MB
netdata                 1       86.27MB
xfdesktop               0.9     72.97MB
named                   0.7     62.42MB
bash                    0.1     55.98MB
xfce4-terminal          0.6     48.01MB
xfce4-panel             0.3     29.39MB
scp-dbus-servic         0.3     28.46MB
xfce4-notifyd           0.3     24.22MB
panel-27-weathe         0.2     22.48MB
blueman-applet          0.2     22.46MB
xfwm4                   0.2     22.41MB
python                  0.2     22.00MB


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