Proxmox Backup Server - memory hungry?

[Spoonman2002]

Hi,

I run Proxmox Backup Server (as a vm) on my Synology NAS.
Runs perfect no problems.
However..... I notice a huge consumption in memory RAM usage.
It is showing +70% RAM usage when it is in idle and doing almost nothing.
Once a week a backup job runs, thats it.
After a reboot of the PBS the RAM usage is very low, but after a couple of hours it increases heaviliy.
Any ideas?

 

[dcsapak]

whats the output of

proxmox-backup-manager versions --verbose

?

we recently tuned the default allocator to have better memory behaviour, that might improve things..
otherwise, what exactly is using up the memory? you can check e.g. with htop/top and sort by the 'RSS'/%MEM column

 

[Spoonman2002]

I did some testing:
when PBS is running after a reboot, RAM usage is low (6%). That's fine.
When I run a backup job (5-6 vm's) the RAM usage (after that job has finished) increases to 60% and stays at 60%.
No decrease in RAM usage after a while.

 

[Spoonman2002]

whats the output of

proxmox-backup-manager versions --verbose

?

we recently tuned the default allocator to have better memory behaviour, that might improve things..
otherwise, what exactly is using up the memory? you can check e.g. with htop/top and sort by the 'RSS'/%MEM column

root@pbs:~# proxmox-backup-manager versions --verbose
proxmox-backup 2.1-1 running kernel: 5.13.19-6-pve
proxmox-backup-server 2.1.5-1 running version: 2.1.5
pve-kernel-helper 7.1-13
pve-kernel-5.13 7.1-9
pve-kernel-5.11 7.0-10
pve-kernel-5.13.19-6-pve 5.13.19-14
pve-kernel-5.13.19-5-pve 5.13.19-13
pve-kernel-5.13.19-2-pve 5.13.19-4
pve-kernel-5.11.22-7-pve 5.11.22-12
pve-kernel-5.11.22-1-pve 5.11.22-2
ifupdown2 3.1.0-1+pmx3
libjs-extjs 7.0.0-1
proxmox-backup-docs 2.1.5-1
proxmox-backup-client 2.1.5-1
proxmox-mini-journalreader 1.2-1
proxmox-widget-toolkit 3.4-7
pve-xtermjs 4.16.0-1
smartmontools 7.2-1
zfsutils-linux 2.1.2-pve1

 

[dcsapak]

ok the version should include that tuning already.
please check with top/htop which process uses the memory

most probably it's the kernels page cache which is filled during the backup
when there is no memory pressure from other applications, the kernel will not free the ram by itself..

 

[Spoonman2002]

ok the version should include that tuning already.
please check with top/htop which process uses the memory

most probably it's the kernels page cache which is filled during the backup
when there is no memory pressure from other applications, the kernel will not free the ram by itself..

these 2 processes take the most MEM% (htop):

/usr/lib/x86_64-linux-gnu/proxmox-backup/proxmox-backup-proxy
/usr/lib/x86_64-linux-gnu/proxmox-backup/proxmox-backup-api

 

[dcsapak]

ok and how much exactly? and how much memory do you have?

 

[Spoonman2002]

ok and how much exactly? and how much memory do you have?

/usr/lib/x86_64-linux-gnu/proxmox-backup/proxmox-backup-proxy = 2.0%
/usr/lib/x86_64-linux-gnu/proxmox-backup/proxmox-backup-api = 1.2%

total memory allocated to PBS is 2GB:
root@pbs:~# free -h
total used free shared buff/cache available
Mem: 1.9Gi 1.1Gi 380Mi 0.0Ki 438Mi 662Mi
Swap: 1.9Gi 0B 1.9Gi

(The PBS runs as a virtual machine in Synology DSM 6.2.4 on a DS220+ with 6GB RAM).

 

[dcsapak]

ok 2% and 1.2% is not really much: its ~50 and ~25 MiB respectively

also the output shows that 662MiB is available
do you use zfs ? if yes that uses up to 50% by default, and the page cache gets filled too

 

[manilx]

Hi

using backup server on a proxmox vm and I'mseeing the same behavior.
Memory (8GB or whatever I add to it) after a while is in the red and stays there.
All working fine with daily backups but the memory thing is strange.

 

[dcsapak]

that memory is used by cache (the yellow part of the htop graph on the top) so this is the default linux kernel behaviour, and has nothing to do with pbs taking up memory
(the pbs daemons use 0.7 and 0.5% which come out to 8GiB * 1.2% ~ 98MiB)

 

[manilx]

that memory is used by cache (the yellow part of the htop graph on the top) so this is the default linux kernel behaviour, and has nothing to do with pbs taking up memory
(the pbs daemons use 0.7 and 0.5% which come out to 8GiB * 1.2% ~ 98MiB)

OK, thx.

All normal then.