11:41 a.m.
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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
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<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>
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