4:05 p.m.
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Hi Franando,
So let's go with the following scenarios:
1. Let's say you have two servers (replication factor is 2), i.e. two
bricks per volume, in this case it is strongly recommended to have the
arbiter node, the metadata storage that will guarantee avoiding the
split brain situation, in this case for arbiter you don't even need a
disk with lots of space, it's enough to have a tiny ssd but hosted on a
separate server. Advantage of such setup is that you don't need the RAID
1 for each brick, you have the metadata information stored in arbiter
node and brick replacement is easy.
2. If you have odd number of bricks (let's say 3, i.e. replication
factor is 3) in your volume and you didn't create the arbiter node as
well as you didn't configure the quorum, in this case the entire load
for keeping the consistency of the volume resides on all 3 servers, each
of them is important and each brick contains key information, they need
to cross-check each other (that's what people usually do with the first
try of gluster :) ), in this case replacing a brick is a big pain and in
this case RAID 1 is a good option to have (that's the disadvantage, i.e.
loosing the space and not having the JBOD option) advantage is that you
don't have the to have additional arbiter node.
3. You have odd number of bricks and configured arbiter node, in this
case you can easily go with JBOD, however a good practice would be to
have a RAID 1 for arbiter disks (tiny 128GB SSD-s ar perfectly
sufficient for volumes with 10s of TB-s in size.)
That's basically it
The rest about the reliability and setup scenarios you can find in
gluster documentation, especially look for quorum and arbiter node
configs+options.
Cheers
Erekle
P.S. What I was mentioning, regarding a good practice is mostly related
to the operations of gluster not installation or deployment, i.e. not
the conceptual understanding of gluster (conceptually it's a JBOD system).
On 08/07/2017 05:41 PM, FERNANDO FREDIANI wrote:
Thanks for the clarification Erekle.
However I get surprised with this way of operating from GlusterFS as
it adds another layer of complexity to the system (either a hardware
or software RAID) before the gluster config and increase the system's
overall costs.
An important point to consider is: In RAID configuration you already
have space 'wasted' in order to build redundancy (either RAID 1, 5, or
6). Then when you have GlusterFS on the top of several RAIDs you have
again more data replicated so you end up with the same data consuming
more space in a group of disks and again on the top of several RAIDs
depending on the Gluster configuration you have (in a RAID 1 config
the same data is replicated 4 times).
Yet another downside of having a RAID (specially RAID 5 or 6) is that
it reduces considerably the write speeds as each group of disks will
end up having the write speed of a single disk as all other disks of
that group have to wait for each other to write as well.
Therefore if Gluster already replicates data why does it create this
big pain you mentioned if the data is replicated somewhere else, can
still be retrieved to both serve clients and reconstruct the
equivalent disk when it is replaced ?
Fernando
On 07/08/2017 10:26, Erekle Magradze wrote:
>
> Hi Frenando,
>
> 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.
>
> Cheers
>
> Erekle
>
>
> On 08/07/2017 03:04 PM, FERNANDO FREDIANI wrote:
>>
>> For any RAID 5 or 6 configuration I normally follow a simple gold
>> rule which gave good results so far:
>> - up to 4 disks RAID 5
>> - 5 or more disks RAID 6
>>
>> 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.
>>
>> Anyone can elaborate about Using RAID + GlusterFS and JBOD + GlusterFS.
>>
>> Thanks
>> Regards
>> Fernando
>>
>>
>> On 07/08/2017 03:46, Devin Acosta wrote:
>>>
>>> Moacir,
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> Here is the direct quote from Red Hat when I asked about RAID and
>>> Bricks:
>>> /
>>> /
>>> /"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.” /
>>>
>>> /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. /
>>> /
>>> /
>>> /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. /
>>> /
>>> /
>>> /Please see the attached document that was given to me by Red Hat
>>> to get more information on this. Hope this information helps you./
>>> /
>>> /
>>>
>>> --
>>>
>>> Devin Acosta, RHCA, RHVCA
>>> Red Hat Certified Architect
>>>
>>> On August 6, 2017 at 7:29:29 PM, Moacir Ferreira
>>> (moacirferreira(a)hotmail.com <mailto:moacirferreira@hotmail.com>)
wrote:
>>>
>>>> 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).
>>>>
>>>>
>>>> This said, my first question is: How should I deploy GlusterFS in
>>>> such oVirt scenario? My questions are:
>>>>
>>>>
>>>> 1 - Should I create 3 RAID (i.e.: RAID 5), one on each oVirt node,
>>>> and then create a GlusterFS using them?
>>>>
>>>> 2 - Instead, should I create a JBOD array made of all server's
disks?
>>>>
>>>> 3 - What is the best Gluster configuration to provide for HA while
>>>> not consuming too much disk space?
>>>>
>>>> 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?
>>>>
>>>>
>>>> At the bottom line, what is the good practice for using GlusterFS
>>>> in small pods for enterprises?
>>>>
>>>>
>>>> You opinion/feedback will be really appreciated!
>>>>
>>>> Moacir
>>>>
>>>> _______________________________________________
>>>> Users mailing list
>>>> Users(a)ovirt.org <mailto:Users@ovirt.org>
>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users(a)ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/users
>>
>>
>>
>> _______________________________________________
>> Users mailing list
>> Users(a)ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
>
--
Recogizer Group GmbH
Dr.rer.nat. Erekle Magradze
Lead Big Data Engineering & DevOps
Rheinwerkallee 2, 53227 Bonn
Tel: +49 228 29974555
E-Mail erekle.magradze(a)recogizer.de
Web: www.recogizer.com
Recogizer auf LinkedIn https://www.linkedin.com/company-beta/10039182/
Folgen Sie uns auf Twitter https://twitter.com/recogizer
-----------------------------------------------------------------
Recogizer Group GmbH
Geschäftsführer: Oliver Habisch, Carsten Kreutze
Handelsregister: Amtsgericht Bonn HRB 20724
Sitz der Gesellschaft: Bonn; USt-ID-Nr.: DE294195993
Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen.
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<p>Hi Franando,</p>
<p>So let's go with the following scenarios:</p>
<p>1. Let's say you have two servers (replication factor is 2), i.e.
two bricks per volume, in this case it is strongly recommended to
have the arbiter node, the metadata storage that will guarantee
avoiding the split brain situation, in this case for arbiter you
don't even need a disk with lots of space, it's enough to have a
tiny ssd but hosted on a separate server. Advantage of such setup
is that you don't need the RAID 1 for each brick, you have the
metadata information stored in arbiter node and brick replacement
is easy.</p>
<p>2. If you have odd number of bricks (let's say 3, i.e.
replication factor is 3) in your volume and you didn't create the
arbiter node as well as you didn't configure the quorum, in this
case the entire load for keeping the consistency of the volume
resides on all 3 servers, each of them is important and each brick
contains key information, they need to cross-check each other
(that's what people usually do with the first try of gluster :) ),
in this case replacing a brick is a big pain and in this case RAID
1 is a good option to have (that's the disadvantage, i.e. loosing
the space and not having the JBOD option) advantage is that you
don't have the to have additional arbiter node.</p>
<p>3. You have odd number of bricks and configured arbiter node, in
this case you can easily go with JBOD, however a good practice
would be to have a RAID 1 for arbiter disks (tiny 128GB SSD-s ar
perfectly sufficient for volumes with 10s of TB-s in size.)</p>
<p>That's basically it</p>
<p>The rest about the reliability and setup scenarios you can find
in gluster documentation, especially look for quorum and arbiter
node configs+options.</p>
<p>Cheers</p>
<p>Erekle</p>
<p>P.S. What I was mentioning, regarding a good practice is mostly
related to the operations of gluster not installation or
deployment, i.e. not the conceptual understanding of gluster
(conceptually it's a JBOD system).<br>
</p>
<br>
<div class="moz-cite-prefix">On 08/07/2017 05:41 PM, FERNANDO
FREDIANI wrote:<br>
</div>
<blockquote type="cite"
cite="mid:c7a1c2e1-57c3-9fa5-0710-ebee3f3fa069@upx.com">
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">
<p>Thanks for the clarification Erekle.</p>
<p>However I get surprised with this way of operating from
GlusterFS as it adds another layer of complexity to the system
(either a hardware or software RAID) before the gluster config
and increase the system's overall costs.<br>
</p>
<p>An important point to consider is: In RAID configuration you
already have space 'wasted' in order to build redundancy (either
RAID 1, 5, or 6). Then when you have GlusterFS on the top of
several RAIDs you have again more data replicated so you end up
with the same data consuming more space in a group of disks and
again on the top of several RAIDs depending on the Gluster
configuration you have (in a RAID 1 config the same data is
replicated 4 times).</p>
<p>Yet another downside of having a RAID (specially RAID 5 or 6)
is that it reduces considerably the write speeds as each group
of disks will end up having the write speed of a single disk as
all other disks of that group have to wait for each other to
write as well.<br>
</p>
<p>Therefore if Gluster already replicates data why does it create
this big pain you mentioned if the data is replicated somewhere
else, can still be retrieved to both serve clients and
reconstruct the equivalent disk when it is replaced ?</p>
<p>Fernando<br>
</p>
<br>
<div class="moz-cite-prefix">On 07/08/2017 10:26, Erekle Magradze
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:aa829d07-fa77-3ed9-2500-e33cc01414b6@recogizer.de">
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">
<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>
<blockquote type="cite"
cite="mid:63bac47b-afe6-0258-d3d7-e545a5004c30@upx.com">
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">
<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">
<style>body{font-family:Helvetica,Arial;font-size:13px}</style>
<div id="bloop_customfont"
style="color:rgb(0,0,0);margin:0px"><font face="Input
Mono"><br>
</font></div>
<div id="bloop_customfont"
style="color:rgb(0,0,0);margin:0px"><font face="Input
Mono">Moacir,</font></div>
<div id="bloop_customfont"
style="color:rgb(0,0,0);margin:0px"><font face="Input
Mono"><br>
</font></div>
<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>
<div id="bloop_customfont"
style="color:rgb(0,0,0);margin:0px"><font face="Input
Mono"><br>
</font></div>
<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>
<div id="bloop_customfont"
style="color:rgb(0,0,0);margin:0px"><font face="Input
Mono"><br>
</font></div>
<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
style="font-family:'helvetica
Neue',helvetica;font-size:14px">
<div class="gmail_signature"
style="font-family:'helvetica
Neue',helvetica;font-size:14px">
<div dir="ltr">
<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(a)hotmail.com</a>)
wrote:</p>
<blockquote type="cite"
class="clean_bq"><span>
<div dir="ltr">
<div>
<title></title>
<div id="divtagdefaultwrapper"
style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif"
dir="ltr">
<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>
_______________________________________________ <br>
Users mailing list <br>
<a href="mailto:Users@ovirt.org"
moz-do-not-send="true">Users(a)ovirt.org</a>
<br>
<a
href="http://lists.ovirt.org/mailman/listinfo/users"
moz-do-not-send="true">http://lists.ovirt.org/mailman/listin...
<br>
</div>
</div>
</span></blockquote>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
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moz-do-not-send="true">Users(a)ovirt.org</a>
<a class="moz-txt-link-freetext"
href="http://lists.ovirt.org/mailman/listinfo/users"
moz-do-not-send="true">http://lists.ovirt.org/mailman/listin...
</pre>
</blockquote>
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<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
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moz-do-not-send="true">Users(a)ovirt.org</a>
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</pre>
</blockquote>
<br>
</blockquote>
<br>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Recogizer Group GmbH
Dr.rer.nat. Erekle Magradze
Lead Big Data Engineering & DevOps
Rheinwerkallee 2, 53227 Bonn
Tel: +49 228 29974555
E-Mail <a class="moz-txt-link-abbreviated"
href="mailto:erekle.magradze@recogizer.de">erekle.magradze@recogizer.de</a>
Web: <a class="moz-txt-link-abbreviated"
href="http://www.recogizer.com">www.recogizer.com</a>
Recogizer auf LinkedIn <a class="moz-txt-link-freetext"
href="https://www.linkedin.com/company-beta/10039182/">https...
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-----------------------------------------------------------------
Recogizer Group GmbH
Geschäftsführer: Oliver Habisch, Carsten Kreutze
Handelsregister: Amtsgericht Bonn HRB 20724
Sitz der Gesellschaft: Bonn; USt-ID-Nr.: DE294195993
Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen.
Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben,
informieren Sie bitte sofort den Absender und löschen Sie diese Mail.
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