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
(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
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