Memory allocation in Couchbase

[Haster]

Hi guys.
When I reserve memory for node how it happened? I mean is all it memory really allocated by system?
Or maybe it used some OS mechanisms to reserve but not allocate?

And about per bucket quote, does it only some kind of watermark which Couchbase is checked to not exceed?
Or are there  some memory allocations occurred?

[Aliaksey Kandratsenka]

Both quotas are "just watermarks". Node quota is just bound for sum of bucket quotas. And bucket quota is a bound which couchbase will try "really hard" not to exceed. But memory allocator fragmentation is not taken into account when couchbase decided if it has memory or if it doesn't. That's why giving it 63 gigs of ram out of 64 is some small kind of suicide in operation terms.

[Haster]

Aliaksey,

Thanks a lot for explanation!