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How many OpenVZ containers would you put?
elwebmaster
Member
in General
As the title says, how many OpenVZ containers would you put on a 16GB machine with one HDD (no RAID, no SSD) and two dual-core Xeons, if every VZ is to have max 1GB RAM and be used exclusively for Node.js+MongoDB?
I was thinking 16 (i.e. almost dedicated RAM in this case, aside for the hypervisor itself), but may be I can fit more? The image uses about 512MB when idle and these VMs will be idle most of the time.
Comments
The problem is the single disk. You wont be running a database on a single disk, not to mention 16? CPU is ok for that many containers and RAM, but storage is really bad and your CPU will be 70-90% in a wait state if the databases are really used.
Is there any way to check the disk I/O in Proxmox or otherwise? I can see CPU usage & memory, but not disk I/O. These are not production DBs mind you, it's just for developers to play with, I don't expect very heavy load.
Even with a document DB 16 boxes accessing the disk at once is going to be too much, Mongo isn't magic. You might live with it for dev but imo you're gonna save yourself a lot of headaches by edging for 2/4 drives at least. Shouldn't push you too far out.
Proxmox is debian, just apt-get anything you would like. Besides, the graphs show disk usage too, just go to summary.
Is it the iowait on the CPU graph that shows disk usage? I don't have any disk I/O graph on the summary page:
I get the I/O graph for each individual VM but that doesn't really help me get a sense of how the server overall is performing.
iowait is shown there. Anything above 3% means there might be problems ahead. With a single disk, say 5%.