RegionServer Hbase vs Performance

[#1]

Hi everybody,
I have 3 questions I want to help.
Question 1: Is splitting the hbase region a horizontal division of the table with a capacity of 1GB, because I currently have 3 tables with very little data (2 row and 2 column family, total column: 2 per table) but is divided into 5 regions ?? That's my server test cluster.
Question 2: In my main server cluster, when a regionserver dies, the load balancing set with hbase.balacer.period is 100s, then the time to load-load is 50s. After the regionserver was resurrected, after 1 day it received the region (20), the total region increased from 300 to 320. Why did that load?
Question 3: I have 1 master server and 1 backup master. When I stopped regions regionserver, the master server and back up master swapped places. Why?
Sorry for my bad english

[#2]

Hello @phongnamam 

To your Queries, (I) Split tries to take an approximate centre point of the RowKey for the Region being split. In this manner, Yes, Region Split is a Horizontal Split. By default, each Table would have 1 Regions. You mentioned, you have 3 Tables & 5 Regions. The same is feasible as each Table have 1 Region (Total 3 Regions) & the Hbase:Meta/Hbase:NameSpace Table have 1 Region each, making total 5 Regions. If a Small Table have 5 Regions, It's likely using Split Point. 

(II) When a RegionServer dies, the Regions hosted on the RegionServer are distributed across Live RegionServers & when the RegionServer comes back online, the Master assign Regions to the RegionServer based on Balancer. The Master Logs would show if Balancer is moving Regions as part of Balancing. 

(III) Ideally, Masters shouldn't flip if 1 RegionServer stops. Best approach is to check the Logs of both Masters to see for any issues.

- Smarak