Proxmox is dirty

[AxelTwin]

Hi everybody,
Since my servers burnt in OVH datacenter I had to turn my backup servers into production servers. One is getting overhelmed and is almost stuck with ram usage going straight to 93% after reboot while there is only 3 VM running on it.
I tried to use atop to understand what's going on and it seems very dirty process running on it but I am not sure how to interpret it and how to clean this up.
Anyone can help ?

 

[H4R0]

Well you have to limit zfs arc.

 

[Dunuin]

Run arc_summary to get infos abount your ARC. By default the ARC should use 16GB (50%) of your RAM if your sda and sdb are mirrored using ZFS.

 

[AxelTwin]

Thanks for your reply,
here is the output:

root@proxmox-3:~# arc_summary -p 1

------------------------------------------------------------------------
ZFS Subsystem Report                            Mon Mar 29 19:49:02 2021
Linux 5.4.103-1-pve                                           2.0.3-pve2
Machine: proxmox-3 (x86_64)                                   2.0.3-pve2

WARNING: Pages are deprecated, please use "--section"

ARC status:                                                      HEALTHY
        Memory throttle count:                                         0

ARC size (current):                                    16.5 %    2.6 GiB
        Target size (adaptive):                        16.8 %    2.7 GiB
        Min size (hard limit):                          6.1 %  992.9 MiB
        Max size (high water):                           16:1   16.0 GiB
        Most Frequently Used (MFU) cache size:         32.0 %  791.3 MiB
        Most Recently Used (MRU) cache size:           68.0 %    1.6 GiB
        Metadata cache size (hard limit):              75.0 %   12.0 GiB
        Metadata cache size (current):                  4.7 %  580.6 MiB
        Dnode cache size (hard limit):                 10.0 %    1.2 GiB
        Dnode cache size (current):                     3.2 %   39.6 MiB

ARC hash breakdown:
        Elements max:                                               3.7M
        Elements current:                              13.0 %     475.4k
        Collisions:                                                36.5M
        Chain max:                                                     8
        Chains:                                                    24.9k

ARC misc:
        Deleted:                                                   23.1M
        Mutex misses:                                               1.4k
        Eviction skips:                                            71.4k

Arc was already set to

options zfs zfs_arc_max=17179869184

 

[Ramalama]

https://en.m.wikipedia.org/wiki/Slab_allocation
12,8gb slab (free)
4gb zfs
220mb buffer
1,4gb cache
720mb free
= ~10gb vm's

 

[AxelTwin]

Thanks Ramalama but not sure I got what you meant with that.
I read some topic relaed to slab issue with proxmox but I guess it is above my competence.
Just in case you can help a bit more, find attached the output of
cat /proc/slabinfo