"total size of all databases that reside on this volume to the maximum size specified, in MB" >> What is meant by all databases? does it sum up the file size of all tsidx file?
Does it include everything in an index/db folder, which would include bloomfilter, .lex & .data files and rawdata folder
maxVolumeDataSizeMB = <positive integer> * If set, this setting limits the total size of all databases that reside on this volume to the maximum size specified, in MB. Note that this it will act only on those indexes which reference this volume, not on the total size of the path set in the 'path' setting of this volume. * If the size is exceeded, splunkd removes buckets with the oldest value of latest time (for a given bucket) across all indexes in the volume, until the volume is below the maximum size. This is the trim operation. This can cause buckets to be chilled [moved to cold] directly from a hot DB, if those buckets happen to have the least value of latest-time (LT) across all indexes in the volume.