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<p>Hi Frenando,</p>
<p>Here is my experience, if you consider a particular hard drive as
a brick for gluster volume and it dies, i.e. it becomes not
accessible it's a huge hassle to discard that brick and exchange
with another one, since gluster some tries to access that broken
brick and it's causing (at least it cause for me) a big pain,
therefore it's better to have a RAID as brick, i.e. have RAID 1
(mirroring) for each brick, in this case if the disk is down you
can easily exchange it and rebuild the RAID without going offline,
i.e switching off the volume doing brick manipulations and
switching it back on.<br>
</p>
<p>Cheers</p>
<p>Erekle<br>
</p>
<br>
<div class="moz-cite-prefix">On 08/07/2017 03:04 PM, FERNANDO
FREDIANI wrote:<br>
</div>
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cite="mid:63bac47b-afe6-0258-d3d7-e545a5004c30@upx.com">
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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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<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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<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
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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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