swap strange behaviour

[emanuelebruno]

Hi to all, I have a production server proxmox 2.1 based, and I have discovered that the swap file doesn't work in my containers. If a create a container debian or centos based and trying to test it with the instructions of this website http://unix.stackexchange.com/questions/1367/how-to-test-swap-partition , I have seen that the swap file is never used from the container.

My proxmox version is this:

pve-manager: 2.1-1 (pve-manager/2.1/f9b0f63a)
running kernel: 2.6.32-11-pve
proxmox-ve-2.6.32: 2.0-66
pve-kernel-2.6.32-11-pve: 2.6.32-66
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.3-1
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.8-3
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.7-2
pve-cluster: 1.0-26
qemu-server: 2.0-39
pve-firmware: 1.0-15
libpve-common-perl: 1.0-27
libpve-access-control: 1.0-21
libpve-storage-perl: 2.0-18
vncterm: 1.0-2
vzctl: 3.0.30-2pve5
vzprocps: 2.0.11-2
vzquota: 3.0.12-3
pve-qemu-kvm: 1.0-9
ksm-control-daemon: 1.1-1

Anybody can you help me?

 

[dietmar]

OpenVZ does not use a swap partition - it just simulates a 'virtual' swap.

Please use KVM if you want to use a real swap partition.

 

[emanuelebruno]

Perhaps I have discovered the problem: taking a look to /etc/fstab file I have noticed that my production server is configured without swap partition; the following is the screenshot of mine fstab:
Do you think that I can add a file swap?

I want to proceed in this way (my production server is an i7 with 24 GB di ram):

dd if=/dev/zero of=/swapfile bs=24M count=1024
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

After that I suppose I have to add to /etc/fstab the following line:
/swapfile swap swap defaults 0 0

I'm scared to apply these settings because I have a production server... Do you think that I will meet some problem after reboot?

 

[udo]

Perhaps I have discovered the problem: taking a look to /etc/fstab file I have noticed that my production server is configured without swap partition; the following is the screenshot of mine fstab: View attachment 1247
Do you think that I can add a file swap?

I want to proceed in this way (my production server is an i7 with 24 GB di ram):

dd if=/dev/zero of=/swapfile bs=24M count=1024
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile

After that I suppose I have to add to /etc/fstab the following line:
/swapfile swap swap defaults 0 0

I'm scared to apply these settings because I have a production server... Do you think that I will meet some problem after reboot?

Hi,
better performance (ok, if swapping start the performance are allways bad) is with an swap-partition.
Look with

vgs
lvs

perhaps you have allready an logical volume for swap, or enough free space in the volume group (leaf enough free space in the VG for snapshots (backup)).

Udo