Exactly Moacir, that is my point.
A proper Distributed FIlesystem should not rely on any type of RAID as
it can make its own redundancy without having to rely on any underneath
layer (look at CEPH). Using RAID may help with management and in certain
scenarios to replace a faulty disk, but at a cost, not cheap by the way.
That's why in terms of resourcing saving, if a replica 3 brings those
issues mentioned it is much worth to have a small arbiter somewhere
instead of wasting a significant amount of disk space.
Fernando
On 08/08/2017 06:09, Moacir Ferreira wrote:
Fernando,
Let's see what people say... But this is what I understood Red Hat
says is the best performance model. This is the main reason to open
this discussion because as long as I can see, some of you in the
community, do not agree.
But when I think about a "distributed file system", that can make any
number of copies you want, it does not make sense using a RAIDed
brick, what it makes sense is to use JBOD.
Moacir
------------------------------------------------------------------------
*From:* fernando.fredi...@upx.com.br <fernando.fredi...@upx.com.br> on
behalf of FERNANDO FREDIANI <fernando.fredi...@upx.com>
*Sent:* Tuesday, August 8, 2017 3:08 AM
*To:* Moacir Ferreira
*Cc:* Colin Coe; users@ovirt.org
*Subject:* Re: [ovirt-users] Good practices
Moacir, I understand that if you do this type of configuration you
will be severely impacted on storage performance, specially for
writes. Even if you have a Hardware RAID Controller with Writeback
cache you will have a significant performance penalty and may not
fully use all the resources you mentioned you have.
Fernando
2017-08-07 10:03 GMT-03:00 Moacir Ferreira <moacirferre...@hotmail.com
<mailto:moacirferre...@hotmail.com>>:
Hi Colin,
Take a look on Devin's response. Also, read the doc he shared that
gives some hints on how to deploy Gluster.
It is more like that if you want high-performance you should have
the bricks created as RAID (5 or 6) by the server's disk
controller and them assemble a JBOD GlusterFS. The attached
document is Gluster specific and not for oVirt. But at this point
I think that having SSD will not be a plus as using the RAID
controller Gluster will not be aware of the SSD. Regarding the OS,
my idea is to have a RAID 1, made of 2 low cost HDDs, to install it.
So far, based on the information received I should create a single
RAID 5 or 6 on each server and then use this disk as a brick to
create my Gluster cluster, made of 2 replicas + 1 arbiter. What is
new for me is the detail that the arbiter does not need a lot of
space as it only keeps meta data.
Thanks for your response!
Moacir
------------------------------------------------------------------------
*From:* Colin Coe <colin....@gmail.com <mailto:colin....@gmail.com>>
*Sent:* Monday, August 7, 2017 12:41 PM
*To:* Moacir Ferreira
*Cc:* users@ovirt.org <mailto:users@ovirt.org>
*Subject:* Re: [ovirt-users] Good practices
Hi
I just thought that you'd do hardware RAID if you had the
controller or JBOD if you didn't. In hindsight, a server with
40Gbps NICs is pretty likely to have a hardware RAID controller.
I've never done JBOD with hardware RAID. I think having a single
gluster brick on hardware JBOD would be riskier than multiple
bricks, each on a single disk, but thats not based on anything
other than my prejudices.
I thought gluster tiering was for the most frequently accessed
files, in which case all the VMs disks would end up in the hot
tier. However, I have been wrong before...
I just wanted to know where the OS was going as I didn't see it
mentioned in the OP. Normally, I'd have the OS on a RAID1 but in
your case thats a lot of wasted disk.
Honestly, I think Yaniv's answer was far better than my own and
made the important point about having an arbiter.
Thanks
On Mon, Aug 7, 2017 at 5:56 PM, Moacir Ferreira
<moacirferre...@hotmail.com <mailto:moacirferre...@hotmail.com>>
wrote:
Hi Colin,
I am in Portugal, so sorry for this late response. It is quite
confusing for me, please consider:
*
*1*- *What if the RAID is done by the server's disk
controller, not by software?
2 -**For JBOD I am just using gdeploy to deploy it. However, I
am not using the oVirt node GUI to do this.
3 -**As the VM .qcow2 files are quite big, tiering would only
help if made by an intelligent system that uses SSD for chunks
of data not for the entire .qcow2 file. But I guess this is a
problem everybody else has. So, Do you know how tiering works
in Gluster?
4 - I am putting the OS on the first disk. However, would you
do differently?
Moacir
------------------------------------------------------------------------
*From:* Colin Coe <colin....@gmail.com
<mailto:colin....@gmail.com>>
*Sent:* Monday, August 7, 2017 4:48 AM
*To:* Moacir Ferreira
*Cc:* users@ovirt.org <mailto:users@ovirt.org>
*Subject:* Re: [ovirt-users] Good practices
1) RAID5 may be a performance hit-
2) I'd be inclined to do this as JBOD by creating a
distributed disperse volume on each server. Something like
echo gluster volume create dispersevol disperse-data 5
redundancy 2 \
$(for SERVER in a b c; do for BRICK in $(seq 1 5); do echo -e
"server${SERVER}:/brick/brick-${SERVER}${BRICK}/brick \c";
done; done)
3) I think the above.
4) Gluster does support tiering, but IIRC you'd need the same
number of SSD as spindle drives. There may be another way to
use the SSD as a fast cache.
Where are you putting the OS?
Hope I understood the question...
Thanks
On Sun, Aug 6, 2017 at 10:49 PM, Moacir Ferreira
<moacirferre...@hotmail.com
<mailto:moacirferre...@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@ovirt.org <mailto:Users@ovirt.org>
http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>
_______________________________________________
Users mailing list
Users@ovirt.org <mailto:Users@ovirt.org>
http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>
_______________________________________________
Users mailing list
Users@ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
