On 03/05/2012 09:39 AM, [email protected] wrote:
Date: Mon, 5 Mar 2012 10:29:22 +0100
From: samuel<[email protected]>
Subject: [Gluster-users] adding bricks of diferent size to gluster
To:[email protected]
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<CAOg=wdch3b72zn54b-11jq_fpbf6mde8qv86p1kfbg4jy76...@mail.gmail.com>
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Dear all,
I've been trying to locate documentation about gluster functionality about
using bricks of diferent sizes and did not find anything useful.
What I was trying to answer was:
*How does using bricks of different size in a distributed replicated volume
affects performance?
I think I read somewhere that it was highly advisable to use bricks of the
same size but I can not locate where I read such statement? Is it true?
Case it's depending on the version, I'm using mostly 3.2.4 version.
Thank in advance,
Samuel.
Samuel,
The mechanism described in the following gluster-users posting describes
how non uniform brick sizes are managed by GlusterFS.
http://gluster.org/pipermail/gluster-users/2011-September/008754.html
I don't know if this approach carries a performance penalty, but I
decided to move away from non uniform brick sizes because this
configuration is not rigorously tested by the developers, as explained
in the gluster-users posting below.
http://gluster.org/pipermail/gluster-users/2011-May/007788.html
The posting below describes how I have set up uniform brick sizes
despite having different sized servers in my cluster.
http://gluster.org/pipermail/gluster-users/2011-August/008597.html
If you are considering using non uniform brick sizes please make sure
that you set the min-free-disk parameter to an appropriate value in
gigabytes. I originally had non uniform brick sizes in my cluster and I
had a lot of problems with small bricks filling up before larger bricks,
resulting in "device full" errors even when there was plenty of space
left in the volume. The solution I eventually found is described in the
following gluster-users posting.
http://gluster.org/pipermail/gluster-users/2011-November/009176.html
The "device full" problem was caused by the default value of
min-free-disk being defined as a percentage rather than as a value in
gigabytes. To set the min-free-disk parameter to a value in GB follow
the instructions described in the following gluster-users postings.
http://gluster.org/pipermail/gluster-users/2011-May/007794.html
http://gluster.org/pipermail/gluster-users/2011-August/008579.html
It is important to make sure the value of min-free-disk is big enough.
I found that setting the value to 10% of the size of the smallest brick
seemed to work, but when I set it to only ~1% of the brick size I still
had problems with "device full" errors.
I hope this helps.
-Dan.
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