When a Couchbase bucket data gets ejected and how to set the ejection thresholds :
If a bucket’s memory quota is exceeded, items may be ejected from the bucket by the Data Service.
For each bucket, available memory is managed according to two watermarks, which are mem_low_wat and mem_high_wat.
Based on the bucket’s configuration, items can be ejected from the bucket, the Data Service ejects items from the bucket until the quantity of data has decreased to the mem_low_wat watermark.
Warning: Couchbase Support, do not recommend that you change the ejection defaults unless required by them.
Note: Changes of thresholds are NOT persistent and must be reapplied after the bucket warmup.
cbepctl [localhost]:11210 -b [bucket-name] -p [bucket-password] set flush_param [parameter] [value]
Parameters used for changing ejection thresholds:
-mem_low_wat -mem_high_wat -pager_active_vb_pcnt