| Re: OpenVZ Density [message #32286 is a reply to message #32275] |
Wed, 30 July 2008 11:20   |
hm2k
Messages: 32
Registered: August 2006
Location: UK
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| dowdle wrote on Tue, 29 July 2008 23:25 |
Well, if you are one who doesn't want to overcommit your RAM, just take the amount of RAM you have and divide it by the amount of RAM you want each container to have. Oh, btw... your RAM includes swap so don't forget to include that in your calculation.
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8000MB RAM/128MB RAM = 62.5 containers...
How does that ensure I don't overcommit?
What do you mean RAM includes swap? How would I include that into the calculation?
| dowdle wrote on Tue, 29 July 2008 23:25 |
You might want to run a few vzsplit commands and see how it parcels things out.
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http://man.cx/vzsplit(
Not sure how this helps...?
| dowdle wrote on Tue, 29 July 2008 23:25 |
There isn't a real formula for container density because what services you run in a container and the resources it needs may vary greatly from container to container.
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Not if all the containers are identical.
| dowdle wrote on Tue, 29 July 2008 23:25 |
The scenarios you see in some of the examples are using the minimal config template I believe... and like you mentioned, they are pretty worthless for real world deployments... but you should be able to install a minimal OS Template in them... that has almost nothing running when it starts up. I believe I saw one OS Template, don't remember which, that had like 3 processes running at startup. You can probably fit that in ~6MB of RAM.
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The example given apparently runs init, syslogd, crond, sshd and Apache. I suspect it's more than 6MB of RAM, but I haven't tested it.
Perhaps I will...
| dowdle wrote on Tue, 29 July 2008 23:25 |
I have a two containers that basically run minimal services plus apache as a Linux distro repo server... and they seem to use about 48MB of RAM when I look at them... but I'm sure there are times when they use more. I have given them much more RAM than they use... because on the host nodes they are running on there is a surplus of resources.
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Even m0n0wall, one of the smallest OS's I know requires 64MB of ram to run... It is however, FreeBSD based, not linux...
For linux, Damn Small Linux requires 8MB RAM to run too...
But then neither of these are even supported by OpenVZ...
The smallest precreated template that openvz supplies is mandriva-2006-i386-minimal.tar.gz - it's system requirements are minimum of 256mb of ram... See: http://www.mandriva.com/archives/en/linux/spring/system_requ irements.html
Beyond that is centos-4-i386-minimal.tar.gz, but I was unable to find the system requirements for that or it's rhel counterpart.
In conclusion I have yet to make any progress on resolving this.
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