well, nice one :)
step chooseleaf firstn 0 type host - it is the part of default crush map (3 hosts, 2 OSDs per host)
It means: write 3 replicas (in my case) to 3 hosts...and randomly select OSD from each host ?
I already read all the docs...and still not sure how to proceed...
On 16 October 2013 23:27, Mike Dawson <mike.dawson@xxxxxxxxxxxx> wrote:
Andrija,
You can use a single pool and the proper CRUSH rule
step chooseleaf firstn 0 type host
to accomplish your goal.
http://ceph.com/docs/master/rados/operations/crush-map/
Cheers,
Mike Dawson
On 10/16/2013 5:16 PM, Andrija Panic wrote:
_______________________________________________Hi,
I have 2 x 2TB disks, in 3 servers, so total of 6 disks... I have
deployed total of 6 OSDs.
ie:
host1 = osd.0 and osd.1
host2 = osd.2 and osd.3
host4 = osd.4 and osd.5
Now, since I will have total of 3 replica (original + 2 replicas), I
want my replica placement to be such, that I don't end up having 2
replicas on 1 host (replica on osd0, osd1 (both on host1) and replica on
osd2. I want all 3 replicas spread on different hosts...
I know this is to be done via crush maps, but I'm not sure if it would
be better to have 2 pools, 1 pool on osd0,2,4 and and another pool on
osd1,3,5.
If possible, I would want only 1 pool, spread across all 6 OSDs, but
with data placement such, that I don't end up having 2 replicas on 1
host...not sure if this is possible at all...
Is that possible, or maybe I should go for RAID0 in each server (2 x 2Tb
= 4TB for osd0) or maybe JBOD (1 volume, so 1 OSD per host) ?
Any suggesting about best practice ?
Regards,
--
Andrija Panić
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Andrija Panić
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