32bit vs 64bit containers

L

luison

Renowned Member
Feb 22, 2010
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elsurexiste.com
I am uncertain about the real limitations/advantages of having OpenVZ containers running 32bit vs 64bit templates.
My doubt raised after trying some mysqltuner on a Debain container that reported:

Code: 
[!!] Switch to 64-bit OS - MySQL cannot currently use all of your RAM

Are there any difference/limitations of the containers handling memory or resources?
Should all guest containers now be 64bits?
 
If your container has more than 4 GB of RAM you should use 64bit. If you are short for memory and trying to save each MB in the container, use 32bit. For performance use 64bit, as your main kernel is 64bit and the processor must switch between the modes, which is not so effective (and some programs, for example, mysql, has noticeable performance boost in 64bit mode due to larger operand sizes)
 
This thread which (I never found before) http://forum.proxmox.com/threads/677-64bits-images-possible?highlight=ssh clarified a lot about the issue.
Basically PVE developers consider 64 bit containers can "waste" a lot of RAM without a proportional return in system speed !
My concern is basically now the 4Gb limit... as one of my system is running one main VM which I would like to have as much resources available as possible. I am now considering splitting the machines and perhaps MySQL server on a dedicated system on 64bits.

By the way this leads me to two suggestions to the great PVE staff:

- some specifications on the wiki about the pros and cons of each extracted from previous thread would help a lot.
- a better search system for the forum (quite pathetic now) would help reduce the number of posts already answered.

Thanks.
 
luison said:
This thread which (I never found before) http://forum.proxmox.com/threads/677-64bits-images-possible?highlight=ssh clarified a lot about the issue.
Basically PVE developers consider 64 bit containers can "waste" a lot of RAM without a proportional return in system speed !
My concern is basically now the 4Gb limit... as one of my system is running one main VM which I would like to have as much resources available as possible. I am now considering splitting the machines and perhaps MySQL server on a dedicated system on 64bits.
Click to expand...
Hi,
but be sure that you speed up your workflow. Because the DB-access over sockets/loopback-device is much faster than via real network (which is used with an dedicated db-server).
By the way this leads me to two suggestions to the great PVE staff:

- some specifications on the wiki about the pros and cons of each extracted from previous thread would help a lot.
Click to expand...
It's an wiki - you can also extend the entrys.
- a better search system for the forum (quite pathetic now) would help reduce the number of posts already answered.

Thanks.
Click to expand...
right - the search function is not the best...

Udo
 
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