(I wrote it freehand, test before applying)
If your goal is to have a replication of 3 on a row and to be able to
switch to the secondary row, then you need 2 roles and you change the crush
rule on the pool side :
rule primary_location {
(...)
step take primary class ssd
step chooseleaf firstn 0 type host
step emit
}
rule secondary_loc {
(...)
step take secondary ...
If the aim is to make a replica 2 on 2 rows (not recommended) :
rule row_repli {
(...)
step take default class ssd
step chooseleaf firstn 0 type row
step emit
}
If the aim is to distribute replications over the 2 rows (for example 2*2
or 2*3 replica) :
type replicated
step take primary class ssd
step chooseleaf firstn 2 type host
step emit
step take secondary class ssd
step chooseleaf firstn 2 type host
step emit
as far as erasure code is concerned, I really don't see what's reasonably
possible on this architecture.
________________________________________________________
Cordialement,
*David CASIER*
________________________________________________________
Le jeu. 9 nov. 2023 à 08:48, Albert Shih <[email protected]> a écrit :
> Le 08/11/2023 à 19:29:19+0100, David C. a écrit
> Hi David.
>
> >
> > What would be the number of replicas (in total and on each row) and their
> > distribution on the tree ?
>
> Well “inside” a row that would be 3 in replica mode.
>
> Between row...well two ;-)
>
> Beside to understanding how to write a rule a little more complex than the
> example in the official documentation, they are another purpose and it's
> to try to have
> a protocole for changing the hardware.
>
> For example if «row primary» are only with old bare metal server, and I
> have some new server I put inside the ceph and want to copy everything
> from the “row primary” to “row secondary”.
>
> Regards
>
> >
> >
> > Le mer. 8 nov. 2023 à 18:45, Albert Shih <[email protected]> a
> écrit :
> >
> > Hi everyone,
> >
> > I'm totally newbie with ceph, so sorry if I'm asking some stupid
> question.
> >
> > I'm trying to understand how the crush map & rule work, my goal is
> to have
> > two groups of 3 servers, so I'm using “row” bucket
> >
> > ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT
> PRI-AFF
> > -1 59.38367 root default
> > -15 59.38367 zone City
> > -17 29.69183 row primary
> > -3 9.89728 host server1
> > 0 ssd 3.49309 osd.0 up 1.00000
> 1.00000
> > 1 ssd 1.74660 osd.1 up 1.00000
> 1.00000
> > 2 ssd 1.74660 osd.2 up 1.00000
> 1.00000
> > 3 ssd 2.91100 osd.3 up 1.00000
> 1.00000
> > -5 9.89728 host server2
> > 4 ssd 1.74660 osd.4 up 1.00000
> 1.00000
> > 5 ssd 1.74660 osd.5 up 1.00000
> 1.00000
> > 6 ssd 2.91100 osd.6 up 1.00000
> 1.00000
> > 7 ssd 3.49309 osd.7 up 1.00000
> 1.00000
> > -7 9.89728 host server3
> > 8 ssd 3.49309 osd.8 up 1.00000
> 1.00000
> > 9 ssd 1.74660 osd.9 up 1.00000
> 1.00000
> > 10 ssd 2.91100 osd.10 up 1.00000
> 1.00000
> > 11 ssd 1.74660 osd.11 up 1.00000
> 1.00000
> > -19 29.69183 row secondary
> > -9 9.89728 host server4
> > 12 ssd 1.74660 osd.12 up 1.00000
> 1.00000
> > 13 ssd 1.74660 osd.13 up 1.00000
> 1.00000
> > 14 ssd 3.49309 osd.14 up 1.00000
> 1.00000
> > 15 ssd 2.91100 osd.15 up 1.00000
> 1.00000
> > -11 9.89728 host server5
> > 16 ssd 1.74660 osd.16 up 1.00000
> 1.00000
> > 17 ssd 1.74660 osd.17 up 1.00000
> 1.00000
> > 18 ssd 3.49309 osd.18 up 1.00000
> 1.00000
> > 19 ssd 2.91100 osd.19 up 1.00000
> 1.00000
> > -13 9.89728 host server6
> > 20 ssd 1.74660 osd.20 up 1.00000
> 1.00000
> > 21 ssd 1.74660 osd.21 up 1.00000
> 1.00000
> > 22 ssd 2.91100 osd.22 up 1.00000
> 1.00000
> >
> > and I want to create a some rules, first I like to have
> >
> > a rule «replica» (over host) inside the «row» primary
> > a rule «erasure» (over host) inside the «row» primary
> >
> > but also two crush rule between primary/secondary, meaning I like to
> have a
> > replica (with only 1 copy of course) of pool from “row” primary to
> > secondary.
> >
> > How can I achieve that ?
> >
> > Regards
> >
> >
> >
> > --
> > Albert SHIH 🦫 🐸
> > mer. 08 nov. 2023 18:37:54 CET
> > _______________________________________________
> > ceph-users mailing list -- [email protected]
> > To unsubscribe send an email to [email protected]
> >
> --
> Albert SHIH 🦫 🐸
> Observatoire de Paris
> France
> Heure locale/Local time:
> jeu. 09 nov. 2023 08:39:41 CET
>
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