[Gluster-users] AFR, writebehind, and debug/trace

[Vikas Gorur]

----- "Barry Jaspan" <barry.jaspan at acquia.com> wrote:

> I just got started with glusterfs.  I read the docs over the weekend 
> 
> and today created a simple setup: two servers exporting a brick and  
> one client mounting them with AFR. I am seeing very poor write  
> performance on a dd test, e.g.:
> 
> time dd if=/dev/zero of=./local-file bs=8192 count=125000

Please try setting the "option cache-size 1MB" option in write-behind. As
Shehjar said, write-behind does not aggregate requests, but merely sends
a reply to the application before the reply from the server has come back.

For reference, this is the kind of performance we get on our test cluster
with the same configuration:

http://dev.gluster.com/~vikas/dd.simple-afr-2.png

Vikas
-- 
Engineer - http://gluster.com/

A: Because it messes up the way people read text.
Q: Why is a top-posting such a bad thing?
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