RAM Sizing formulas are incorrect?
I have a problem with calculation RAM quota.
I use formulas on http://www.couchbase.com/docs/couchbase-manual-1.8/couchbase-bestpractic...
For example I need to create 1 bucket on node...
documents_num = 200000
ID_size = 7
number_of_replicas = 0
working_set_percentage = 100% (all data in RAM)
per_node_ram_quota = 1000Mb
Meta data per document = 120
headroom = 25%
High Water Mark = 70%
So, using formulas I've got 66 Mb Claster RAM quota required.
After that I create bucket with 100 Mb RAM quota (100 > 66, so I thought It would enough). But then I created a bucket
and began to store values ... memory usage parameter rises faster then "user data memory". After that it exceeded "High water mark" parameter, and store key function returned error: "Temporary error. Please try later".
But If I set 200 Mb ram quota for bucket - all is good and all keys have been stored.
So, how I should compute RAM quota? Or maybe it is a bug with memory usage parameter (Why It uses additional memory that needed)?