On Wed, Dec 5, 2018 at 3:32 PM Sergey Dolgov <palz...@gmail.com> wrote:

> Hi guys
>
> I faced strange behavior of crushmap change. When I change crush
> weight osd I sometimes get  increment osdmap(1.2MB) which size is
> significantly bigger than size of osdmap(0.4MB)
>

This is probably because when CRUSH changes, the new primary OSDs for a PG
will tend to set a "pg temp" value (in the OSDMap) that temporarily
reassigns it to the old acting set, so the data can be accessed while the
new OSDs get backfilled. Depending on the size of your cluster, the number
of PGs on it, and the size of the CRUSH change, this can easily be larger
than the rest of the map because it is data with size linear in the number
of PGs affected, instead of being more normally proportional to the number
of OSDs.
-Greg


> I use luminois 12.2.8. Cluster was installed a long ago, I suppose
> that initially it was firefly
> How can I view content of increment osdmap or can you give me opinion
> on this problem. I think that spikes of traffic tight after change of
> crushmap relates to this crushmap behavior
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