8:31 a.m.
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RAID 6 doesn't make exactly 3 copies of data.
I think storage is too expensive when compared to the total cost of the
platform that 3 copies is waste of storage or luxury, given than if you
have a permanent failure you still can make a new 2nd copy of the data
provided you have storage left for that.
On 25/04/2017 10:26, Donny Davis wrote:
I personally want three copies of my data, more akin to RAID 6(ish)
so
in my case replica 3 makes perfect sense.
On Mon, Apr 24, 2017 at 11:34 AM, Denis Chaplygin <dchaplyg(a)redhat.com
<mailto:dchaplyg@redhat.com>> wrote:
Hello!
On Mon, Apr 24, 2017 at 5:08 PM, FERNANDO FREDIANI
<fernando.frediani(a)upx.com <mailto:fernando.frediani@upx.com>> wrote:
Hi Denis, understood.
What if in the case of adding a fourth host to the running
cluster, will the copy of data be kept only twice in any of
the 4 servers ?
replica volumes can be build only from 2 or 3 bricks. There is no
way to make a replica volume from a 4 bricks.
But you may combine distributed volumes and replica volumes [1]:
|gluster volume create test-volume replica 2 transport tcp
server1:/b1 server2:/b2 server3:/b3 server4:/b4|
test-volume would be like a RAID10 - you will have two replica
volumes b1+b2 and b3+b4 combined into a single distributed volume.
In that case you will
have only two copies of your data. Part of your data will be
stored twice on b1 and b2 and another one part will be stored
twice at b3 and b4
You will be able to extend that distributed volume by adding new
replicas.
[1]
https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Setting%20...
<https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Setting%20...
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<p>RAID 6 doesn't make exactly 3 copies of data.</p>
<p>I think storage is too expensive when compared to the total cost
of the platform that 3 copies is waste of storage or luxury, given
than if you have a permanent failure you still can make a new 2nd
copy of the data provided you have storage left for that.</p>
<br>
<div class="moz-cite-prefix">On 25/04/2017 10:26, Donny Davis
wrote:<br>
</div>
<blockquote
cite="mid:CAMHmko9FfZQErKCyg7crth-ZJode9qWC5DgdjcbM7EirVRUHrA@mail.gmail.com"
type="cite">
<div dir="ltr">I personally want three copies of my data, more
akin to RAID 6(ish) so in my case replica 3 makes perfect
sense. </div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Apr 24, 2017 at 11:34 AM, Denis
Chaplygin <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:dchaplyg@redhat.com"
target="_blank">dchaplyg(a)redhat.com</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hello!<br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Apr 24, 2017 at 5:08
PM, FERNANDO FREDIANI <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:fernando.frediani@upx.com"
target="_blank">fernando.frediani(a)upx.com</a>&gt;</span>
wrote:<br>
<blockquote style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex"
class="gmail_quote">
<div bgcolor="#FFFFFF">
<p>Hi Denis, understood.<br>
What if in the case of adding a fourth host to
the running cluster, will the copy of data be
kept only twice in any of the 4 servers ?</p>
</div>
</blockquote>
<div><br>
</div>
<div>replica volumes can be build only from 2 or 3
bricks. There is no way to make a replica volume
from a 4 bricks. <br>
<br>
</div>
<div>But you may combine distributed volumes and
replica volumes [1]:<br>
<br>
<pre><code class="m_4650192000417937643gmail-hljs
m_4650192000417937643gmail-sql">gluster volume <span
class="m_4650192000417937643gmail-hljs-operator"><span
class="m_4650192000417937643gmail-hljs-keyword">create</span>
test-volume replica <span
class="m_4650192000417937643gmail-hljs-number">2</span> transport tcp
server1:/b1 server2:/b2 server3:/b3 server4:/b4</span></code></pre>
test-volume would be like a RAID10 - you will have
two replica volumes b1+b2 and b3+b4 combined into a
single distributed volume. In that case you will<br>
have only two copies of your data. Part of your data
will be stored twice on b1 and b2 and another one
part will be stored twice at b3 and b4<br>
You will be able to extend that distributed volume
by adding new replicas.<br>
<br>
</div>
<div><br>
[1] <a moz-do-not-send="true"
href="https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Setting%20Up%20Volumes/#creating-distributed-replicated-volumes"
target="_blank">https://gluster.readthedocs.<wbr>io/en/latest/Administrator%<wbr>20Guide/Setting%20Up%<wbr>20Volumes/#creating-<wbr>distributed-replicated-volumes</a><br>
</div>
</div>
</div>
</div>
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