[lustre-discuss] Virtual servers

[Jon Tegner]

As I wrote, the situation was improved by moving the client to one of 
the machines where the OSS are running under a virtual instance.

But what could be the reason for this? Seems to me there has to be some 
kind of competition of resources. But what resources?

Would the situation be improved by more memory? Faster CPU or disk? 
While creating the virtual machine number of cores, and amount of memory 
in the virtual machine are specified, should I increase or decrease 
these resources? Are there some kernel settings that could help improve 
the situation? Or maybe some BIOS settings related to the virtual machines?

Just curious here.

Thanks,

/jon

On 02/16/2017 04:55 PM, Mohr Jr, Richard Frank (Rick Mohr) wrote:
>> On Feb 16, 2017, at 9:56 AM, Jon Tegner <tegner at foi.se> wrote:
>>
>> I have three (physical) machines, and each one have a virtual machine on them (KVM). On one of the virtual machines there is an MDS and on two of them there are OSS:es installed.
>>
>> All system use CentOS-7.3 and Lustre 2.9.0, and I mount the file system on one of the physical machines.
>>
> Which machine of you mount the file system on?  Is it an OSS node or the MDS node?
>
>> Anyway, when evaluating the performance (using FIO) I expected to see an increased transfer rate when going from one to two simultaneous files in the tests, and I do see this, but only for very small file sizes (around 0.2 GB). On the "non virtual" file systems I have tested the effect of increased transfer rate as the number of files are increased is on the other hand easily verified.
> Have you tried mounting the file system on different nodes?  This could help determine if the problem is always the same or if it might be affected by the type of node (MDS vs OSS) that is being used for the client.
>
> --
> Rick Mohr
> Senior HPC System Administrator
> National Institute for Computational Sciences
> http://www.nics.tennessee.edu
>
>