Overhead on hard drive resources

Question

OpenVZ

Hello colleagues!
The situation is as follows: there is a server with CentOS6 + OpenVZ
On the server, there is a hard raid for many terabytes.
In the virtual machine in the north, video content is stored, which is distributed by nginx through pseudo-streaming.
When users were allowed to access the resource, and a small enough number, the disk load soared to 100%, which led to terrible brakes.
Experiments with nginx did not noticeably correct the situation, the load was reduced to about 85%
In desperation, they decided to try a strange thing: they put out the container, raised nginx right on the physical machine and pointed the path directly into the extinguished virtual machine with the root directory (/vz/private/1/srv/ www/)

The load dropped to 5-10% with the same attendance.

Tell me, please, does OpenVZ really give such a huge overhead on the hard disk at high loads on the file system?

Is it possible to fix this? Virtualization would be desirable to use nevertheless.

Answer 1

How did you do the virtual disk? raw data?
* for the sake of interest, put proxmox (it's really 10 minutes) and try to create a virtual machine there. the guys optimized the work very well, finished the core ... it makes sense to look at a real overhead

Answer 2

I would also advise you to ask in the official mailing list, if they don’t help, put a bug in the bugzilla openvz.org, although I didn’t have such a problem as you did, but I didn’t run containers without limits either.
Before you write to the mailing list, put the latest kernel, and post the versions of the utilities and the kernel in the mailing list.

Answer 3

try bind mount

Answer 4

Is caching in the virtual machine in nginx turned off for files? Not through proxy pass they are given by chance?

Answer 5

You have a disk connected via simfs in an openvz container.
There is definitely no such big overhead in openvz as you say.

Answer 6

Is it possible to ssh to this machine in the same screen session as you, so that you are not afraid that I will break something for you?