[Gluster-users] Reading not distributed across bricks

Pranith Kumar Karampuri pkarampu at redhat.com
Mon Aug 11 04:53:14 UTC 2014


hi Ray,
   Reads are served from the bricks which respond the fastest at the 
moment. They are not load-balanced.

Pranith
On 08/08/2014 03:06 AM, Ray Mannings wrote:
> Hi,
>
> I have a small (5 node) compute cluster running an MPI job that needs 
> to read from a few 20 GB files. These files are stored in a gluster 
> volume composed of bricks from four storage nodes. I originally made 
> the volume with a replica count of 2, but in an attempt to improve 
> read performance, I recreated it with a replica count of 4.
>
> However, reading turned out to be even slower! I checked out disk 
> access with iotop, and for one file, only two of the bricks are being 
> read from. For another file, only _one_ brick is accessed! Volume top 
> read also shows the same thing.
>
> What might be the problem? There are 40 threads across the cluster 
> trying to read at the same time; shouldn't this be automatically load 
> balanced across each brick?
>
> Thanks,
> Ray
>
>
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