71 GB/128 GB RAM used

[TechLineX]

Hello,

2 servers with 2GB RAM are running at our hostsystem (zfs)

RAM usage is 71/128GB. How could this be?

pveversion -v
proxmox-ve: 4.4-76 (running kernel: 4.4.35-1-pve)
pve-manager: 4.4-1 (running version: 4.4-1/eb2d6f1e)
pve-kernel-4.4.35-1-pve: 4.4.35-76
lvm2: 2.02.116-pve3
corosync-pve: 2.4.0-1
libqb0: 1.0-1
pve-cluster: 4.0-48
qemu-server: 4.0-101
pve-firmware: 1.1-10
libpve-common-perl: 4.0-83
libpve-access-control: 4.0-19
libpve-storage-perl: 4.0-70
pve-libspice-server1: 0.12.8-1
vncterm: 1.2-1
pve-docs: 4.4-1
pve-qemu-kvm: 2.7.0-9
pve-container: 1.0-88
pve-firewall: 2.0-33
pve-ha-manager: 1.0-38
ksm-control-daemon: 1.2-1
glusterfs-client: 3.5.2-2+deb8u3
lxc-pve: 2.0.6-2
lxcfs: 2.0.5-pve1
criu: 1.6.0-1
novnc-pve: 0.5-8
smartmontools: 6.5+svn4324-1~pve80
zfsutils: 0.6.5.8-pve13~bpo80

Regards

 

[dcsapak]

zfs can use up to 50% of your ram by default so 128/2 = 64 + 2*2 = 68 + system + caching and your near your 71 GB

you can limit the ram usage of zfs, look here:
https://pve.proxmox.com/wiki/ZFS_on_Linux#_limit_zfs_memory_usage

 

[TechLineX]

zfs can use up to 50% of your ram by default so 128/2 = 64 + 2*2 = 68 + system + caching and your near your 71 GB

you can limit the ram usage of zfs, look here:
https://pve.proxmox.com/wiki/ZFS_on_Linux#_limit_zfs_memory_usage

Hello,

the file /etc/modprobe.d/zfs.conf isn't existing. Is that normally? Is a change possible in the productive system?

Regards

 

[fireon]

the file /etc/modprobe.d/zfs.conf isn't existing. Is that normally? Is a change possible in the productive system?

Yes this is normal, you can change it, but an reboot is required.

 

[TechLineX]

Can I do something without a reboot?

Regards

 

[fabian]

Can I do something without a reboot?

Regards

you can also set the ZFS module parameters at runtime, e.g. with:

echo 123456 > /sys/module/zfs/parameters/zfs_arc_max

 

[TechLineX]

Hello Fabian,

and how is the server comeing down? - If there is a usage like this?

What means 123456?

 

[fabian]

123456 is a placeholder for whatever you want to set as limit - see "man zfs-module-parameters" and/or https://pve.proxmox.com/wiki/ZFS_on_Linux#_limit_zfs_memory_usage fpr details.

 

[TechLineX]

Hello Fabian,

do I have to activate it, like it's said in your Link? And then a reboot isn't neccessary?

It's a productive System.

Regards

 

[morph027]

Jip, just take a serious amount of memory. But normally there's no need to touch it...i mean, that's what memory is for..caching things. And ZFS is freeing up memory when someone else needs it...

 

[TechLineX]

Actally there is a use of about 64 gb RAM only for caching. So I have a hudge usage of RAM. Actually the use is like 97%. If a Customer needs a lot of RAM a time, and the Server goes over the free RAM, the Server will reboot.

How much do you think is enough for caching?

 

[Rhinox]

Server will no go over free RAM, because disk-cache is "low-priority" usage of RAM. If any process needs more RAM then there is free at that moment, cache size will be reduced. That's the way every modern OS works (yes, even windows)...

I trully do not understand this obsession with free RAM. What do you get out of it, if you see plenty of free RAM? Does you system run better? I doubt so. Does it make you feel better? Maybe. Or you get paid money for every free byte of RAM? Don't understand. But what I do understand is this: any meaningful using of RAM is better, than not using it at all...

 

[morph027]

http://www.linuxatemyram.com/

It definitely will not reboot when someone demands memory from FS cache. Even then there's an application eating all the memory the OOM killler will take care of it, also causing no reboot.

 

[TechLineX]

Server will no go over free RAM, because disk-cache is "low-priority" usage of RAM. If any process needs more RAM then there is free at that moment, cache size will be reduced. That's the way every modern OS works (yes, even windows)...

I trully do not understand this obsession with free RAM. What do you get out of it, if you see plenty of free RAM? Does you system run better? I doubt so. Does it make you feel better? Maybe. Or you get paid money for every free byte of RAM? Don't understand. But what I do understand is this: any meaningful using of RAM is better, than not using it at all...

Actually it's not possible to Start a vps with a few gb of RAM.
- Error: Can't allocate Memory

How to work with this Problem?

 

[morph027]

Then there must be something different allocating the memory...other VMs?

Can you post a screenshot of htop? I guess the memory allocation is not from caches...