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<p>For any RAID 5 or 6 configuration I normally follow a simple gold
rule which gave good results so far:<br>
- up to 4 disks RAID 5<br>
- 5 or more disks RAID 6</p>
<p>However I didn't really understand well the recommendation to use
any RAID with GlusterFS. I always thought that GlusteFS likes to
work in JBOD mode and control the disks (bricks) directlly so you
can create whatever distribution rule you wish, and if a single
disk fails you just replace it and which obviously have the data
replicated from another. The only downside of using in this way is
that the replication data will be flow accross all servers but
that is not much a big issue.</p>
<p>Anyone can elaborate about Using RAID + GlusterFS and JBOD +
GlusterFS.</p>
<p>Thanks<br>
Regards<br>
Fernando<br>
</p>
<br>
<div class="moz-cite-prefix">On 07/08/2017 03:46, Devin Acosta
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CANCGKEp4XGs0U+Qs78eEmqCNtvpLY-Azjb5DcGhZ9yiKTBEEfw@mail.gmail.com">
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<div id="bloop_customfont" style="color:rgb(0,0,0);margin:0px"><font
face="Input Mono">Moacir,</font></div>
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face="Input Mono"><br>
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<div id="bloop_customfont" style="color:rgb(0,0,0);margin:0px"><font
face="Input Mono">I have recently installed multiple Red Hat
Virtualization hosts for several different companies, and have
dealt with the Red Hat Support Team in depth about optimal
configuration in regards to setting up GlusterFS most
efficiently and I wanted to share with you what I learned.</font></div>
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face="Input Mono"><br>
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<div id="bloop_customfont" style="color:rgb(0,0,0);margin:0px"><font
face="Input Mono">In general Red Hat Virtualization team
frowns upon using each DISK of the system as just a JBOD, sure
there is some protection by having the data replicated,
however, the recommendation is to use RAID 6 (preferred) or
RAID-5, or at least RAID-1 at the very least.</font></div>
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face="Input Mono"><br>
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<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono">Here is the direct quote from Red Hat when I asked about
RAID and Bricks:</font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i><br>
</i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i>"A typical Gluster configuration would use RAID
underneath the bricks. RAID 6 is most typical as it gives
you 2 disk failure protection, but RAID 5 could be used
too. Once you have the RAIDed bricks, you'd then apply the
desired replication on top of that. The most popular way of
doing this would be distributed replicated with 2x
replication. In general you'll get better performance with
larger bricks. 12 drives is often a sweet spot. Another
option would be to create a separate tier using all SSD’s.” </i></font></div>
<div id="bloop_customfont" style="margin:0px"><br>
</div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i>In order to SSD tiering from my understanding you
would need 1 x NVMe drive in each server, or 4 x SSD hot
tier (it needs to be distributed, replicated for the hot
tier if not using NVME). So with you only having 1 SSD drive
in each server, I’d suggest maybe looking into the NVME
option. </i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i><br>
</i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i>Since your using only 3-servers, what I’d probably
suggest is to do (2 Replicas + Arbiter Node), this setup
actually doesn’t require the 3rd server to have big drives
at all as it only stores meta-data about the files and not
actually a full copy. </i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i><br>
</i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i>Please see the attached document that was given to me
by Red Hat to get more information on this. Hope this
information helps you.</i></font></div>
<div id="bloop_customfont" style="margin:0px"><font face="Input
Mono"><i><br>
</i></font></div>
<br>
<div id="bloop_sign_1502087376725469184" class="bloop_sign"><span
style="font-family:'helvetica Neue',helvetica;font-size:14px">--</span><br
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<div class="gmail_signature" style="font-family:'helvetica
Neue',helvetica;font-size:14px">
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<div><br>
</div>
<div>Devin Acosta, RHCA, RHVCA</div>
<div>Red Hat Certified Architect</div>
</div>
</div>
</div>
<br>
<p class="airmail_on">On August 6, 2017 at 7:29:29 PM, Moacir
Ferreira (<a href="mailto:moacirferreira@hotmail.com"
moz-do-not-send="true">moacirferreira@hotmail.com</a>) wrote:</p>
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<p><span>I am willing to assemble a oVirt "pod", made of
3 servers,
each with 2 CPU sockets of 12 cores, 256GB RAM, 7
HDD 10K, 1 SSD.
The idea is to use GlusterFS to provide HA for the
VMs. The 3
servers have a dual 40Gb NIC and a dual 10Gb NIC. So
my intention
is to create a loop like a server triangle using the
40Gb NICs for
virtualization files (VMs .qcow2) access and to move
VMs around the
pod (east /west traffic) while using the 10Gb
interfaces for giving
services to the outside world (north/south traffic).</span></p>
<p><br>
</p>
<p>This said, my first question is: How should I deploy
GlusterFS
in such oVirt scenario? My questions are:</p>
<p><br>
</p>
<p>1 - Should I create 3 RAID (i.e.: RAID 5), one on
each oVirt
node, and then create a GlusterFS using them?</p>
<p>2 - Instead, should I create a JBOD array made of all
server's
disks?</p>
<p>3 - What is the best Gluster configuration to provide
for HA
while not consuming too much disk space?<br>
</p>
<p>4 - Does a oVirt hypervisor pod like I am planning to
build, and
the virtualization environment, benefits from tiering
when using a
SSD disk? And yes, will Gluster do it by default or I
have to
configure it to do so?</p>
<p><br>
</p>
<p>At the bottom line, what is the good practice for
using
GlusterFS in small pods for enterprises?<br>
</p>
<p><br>
</p>
<p>You opinion/feedback will be really appreciated!</p>
<p>Moacir<br>
</p>
</div>
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