Hi Loic,
Thanks for providing a detailed example. I'm able to run the example
that you provide, and also got my own live crushmap to produce some
results, when I appended the "--num-rep 3" option to the command.
Without that option, even your example is throwing segfaults - maybe a
bug in crushtool?
One other area I wasn't sure about - can the final "chooseleaf" step
specify "firstn 0" for simplicity's sake (and to automatically handle a
larger pool size in future) ? Would there be any downside to this?
Cheers
On 16/09/14 16:20, Loic Dachary wrote:
> Hi Daniel,
>
> When I run
>
> crushtool --outfn crushmap --build --num_osds 100 host straw 2 rack straw 10 default straw 0
> crushtool -d crushmap -o crushmap.txt
> cat >> crushmap.txt <<EOF
> rule myrule {
> ruleset 1
> type replicated
> min_size 1
> max_size 10
> step take default
> step choose firstn 2 type rack
> step chooseleaf firstn 2 type host
> step emit
> }
> EOF
> crushtool -c crushmap.txt -o crushmap
> crushtool -i crushmap --test --show-utilization --rule 1 --min-x 1 --max-x 10 --num-rep 3
>
> I get
>
> rule 1 (myrule), x = 1..10, numrep = 3..3
> CRUSH rule 1 x 1 [79,69,10]
> CRUSH rule 1 x 2 [56,58,60]
> CRUSH rule 1 x 3 [30,26,19]
> CRUSH rule 1 x 4 [14,8,69]
> CRUSH rule 1 x 5 [7,4,88]
> CRUSH rule 1 x 6 [54,52,37]
> CRUSH rule 1 x 7 [69,67,19]
> CRUSH rule 1 x 8 [51,46,83]
> CRUSH rule 1 x 9 [55,56,35]
> CRUSH rule 1 x 10 [54,51,95]
> rule 1 (myrule) num_rep 3 result size == 3: 10/10
>
> What command are you running to get a core dump ?
>
> Cheers
>
> On 16/09/2014 12:02, Daniel Swarbrick wrote:
>> On 15/09/14 17:28, Sage Weil wrote:
>>> rule myrule {
>>> ruleset 1
>>> type replicated
>>> min_size 1
>>> max_size 10
>>> step take default
>>> step choose firstn 2 type rack
>>> step chooseleaf firstn 2 type host
>>> step emit
>>> }
>>>
>>> That will give you 4 osds, spread across 2 hosts in each rack. The pool
>>> size (replication factor) is 3, so RADOS will just use the first three (2
>>> hosts in first rack, 1 host in second rack).
>> I have a similar requirement, where we currently have four nodes, two in
>> each fire zone, with pool size 3. At the moment, due to the number of
>> nodes, we are guaranteed at least one replica in each fire zone (which
>> we represent with bucket type "room"). If we add more nodes in future,
>> the current ruleset may cause all three replicas of a PG to land in a
>> single zone.
>>
>> I tried the ruleset suggested above (replacing "rack" with "room"), but
>> when testing it with crushtool --test --show-utilization, I simply get
>> segfaults. No amount of fiddling around seems to make it work - even
>> adding two new hypothetical nodes to the crushmap doesn't help.
>>
>> What could I perhaps be doing wrong?
>>
>> _______________________________________________
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>> ceph-users at lists.ceph.com
>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>
>
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