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Is HBase block cache dropped when restart HBase?

I am currently confused with the HBase block cache.

I have come to aware about the existence of HBase block cache and it is for read performance. The question is that, if I stop the HBase by command,

stop-hbase.sh

and restart HBase by command,

start-hbase.sh

would it cause dropping all the block caches of HBase and block caches become empty?

Thank you all for advance.

Solution

  • Yes, that's right. HBase BlockCache is instantiated at region server startup and is retained for the entire lifetime of the process.

    If you restart the deamons, you are going to have an empty block cache due to the region server is created again. The data which is always saved is the data which is stored in HFiles.