Spare memory recommendation (for the host)

Dan Schaefer

New Member
May 29, 2012
8
0
1
Akron, Ohio, United States
Simple question(s): How much memory should I leave for the host OS? If I have a host with 8GB RAM and 3 VMs with a total of 6GB RAM allocated, is 2GB enough to leave for the host? Can I allocate another 1GB and still be safe with 7 of 8GB allocated to guests?

# pveversion -v
pve-manager: 2.1-14 (pve-manager/2.1/f32f3f46)
running kernel: 2.6.32-14-pve
proxmox-ve-2.6.32: 2.1-74
pve-kernel-2.6.32-11-pve: 2.6.32-66
pve-kernel-2.6.32-14-pve: 2.6.32-74
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: 3.1.92-3
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.8-1
pve-cluster: 1.0-27
qemu-server: 2.0-49
pve-firmware: 1.0-18
libpve-common-perl: 1.0-30
libpve-access-control: 1.0-24
libpve-storage-perl: 2.0-31
vncterm: 1.0-3
vzctl: 3.0.30-2pve5
vzprocps: 2.0.11-2
vzquota: 3.0.12-3
pve-qemu-kvm: 1.1-8
ksm-control-daemon: 1.1-1
 

mir

Famous Member
Apr 14, 2012
3,559
120
83
Copenhagen, Denmark
Hi,
if you don't use extra services on the host (nfs, samba, backup, ...) 1GB should be enough.
But linux use free mem for caching - so more ram is an good invest.

Udo
I would even think 512MB should be enough for the host depending on that the host does not do anything else.
 

Dan Schaefer

New Member
May 29, 2012
8
0
1
Akron, Ohio, United States
if you don't use extra services on the host (nfs, samba, backup, ...) 1GB should be enough.
But linux use free mem for caching - so more ram is an good invest.
I would even think 512MB should be enough for the host depending on that the host does not do anything else.

Thank you both for your suggestions. 8GB is the RAM size of the current setup, but we have order 16GB to put into it. That should be arriving shortly. The only other services I can think of are:
Bacula Client - Backs up less than 1 MB of config files every night
SCSI Tape drive - Will be used to copy backups to. (Have a post open to troubleshoot allowing the device to pass through to a VM)
USB3 drive shared via NFS (Not able to get USB3 to passthrough to VM. Seems to be a performance issue with NFS)
USB2 drive passed through to a VM

To play it safe, once we get the 16GB, I will leave at least 1.5GB for the host.
 

udo

Famous Member
Apr 22, 2009
5,918
180
83
Ahrensburg; Germany
Thank you both for your suggestions. 8GB is the RAM size of the current setup, but we have order 16GB to put into it. That should be arriving shortly. The only other services I can think of are:
Bacula Client - Backs up less than 1 MB of config files every night
SCSI Tape drive - Will be used to copy backups to. (Have a post open to troubleshoot allowing the device to pass through to a VM)
USB3 drive shared via NFS (Not able to get USB3 to passthrough to VM. Seems to be a performance issue with NFS)
USB2 drive passed through to a VM

To play it safe, once we get the 16GB, I will leave at least 1.5GB for the host.
Hi,
bacula take not very much (150MB for an long running bacula-fd).
BTW. I use an OpenVZ as backup-VM (with bacula) - there are not much trouble to use a tape-jukebox inside an OpenVZ-VM and has also no problems with the IO.
I can't say anything about USB-drives at a server - I don't use that.

Udo
 

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