Hi Strahil,
thanks for you answer - but now I am completely lost :)
From this documentation:
https://docs.oracle.com/cd/E52668_01/F10040/html/gluster-312-volume-distr-disp.html
"As a dispersed volume must have a minimum of three bricks, a
distributed dispersed volume must have at least six bricks. For example,
six nodes with one brick, or three nodes with two bricks on each node
are needed for this volume type."
So for a distributed dispersed volume I need at least six bricks. If
each brick is a RAID6, I have 6 x 2 Parity disks = 12 disks for parity.
In your example you only have one brick per node in a three node setup.
This is no distributed dispersed volume then, right?
A confused Markus
Am 14.01.2020 16:29, schrieb Strahil:
Hi Markus,
Distributed dispersed volume is just LVM's linear LV -> so in case of
brick failiure - you loose the data on it.
Raid 6 requires 2 disks for parity, so you can make a large RAID6
and use that as a single brick - so the disks that hold the parity
data are only 6 ( 3 nodes x 2 disks).
Of course if you have too many disks for a single raid controller
,that you can consider a replica volume with an arbiter.
Best Regards,
Strahil Nikolov
On Jan 14, 2020 13:36, Markus Kern <gluster@xxxxxxxxxxx> wrote:
Greetings again!
After reading RedHat documentation regarding optimizing Gluster
storage
another question comes to my mind:
Let's presume that I want to go the distributed dispersed volume way.
Three nodes which two bricks each.
According to RedHat's recommendation, I should use RAID6 as underlying
RAID for my planned workload.
I am frightened by that "waste" of disks in such a case:
When each brick is a RAID6, I would "loose" two disks per brick - 12
lossed disks in total.
In addition to this, distributed dispersed volume adds another layer
of
lossed disk space.
Am I wrong here? Maybe I didn't understand the recommendations wrong?
Markus
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