| Re: OpenVZ IO Isolation ? [message #43383 is a reply to message #43381] |
Fri, 02 September 2011 18:06   |
seanfulton
Messages: 105
Registered: May 2007
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Senior Member |
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I think the VZ containers should prevent activity inside one container from stopping IO on all other containers. Otherwise, what is the point of containers? For that matter, if the Linux OS can't prevent one task from robbing IO from all other tasks on the system, what is the point of a multi-tasking, multi-user OS?
I think this is a defect, and am not sure why people are so quick to say it is normal Linux or OpenVZ behavior.
Again, the purpose of a multitasking OS to *share* resources. The purpose of OpenVZ is to *share* a server. If a normal, non-privileged user inside one container can launch a non-privileged task that blocks all IO from other containers, including the HN, I think that is a defect.
I have done a bit of research on this and it appears to be a bug in the 2.6.18 kernel source, likely in the x86_64 branch. I've seen many reports from non-OpenVZ users who have problems like this but they seem to resolve themselves through driver updates, firmware updates to the RAID subsystem they are using, etc. Users who are not using a RAID subsystem seem to continue to have the problem. But all of them start with the 2.6.18 kernel, x86_64 version.
Also, this is not a problem in the RHEL6 releases. I have tested by moving a VE from a RHEL5 machine where the problem is demonstrated to a RHEL6 machine and the problem goes away.
sean
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