On Mon, Mar 17, 2014 at 6:01 AM, Linlin Du <[email protected]> wrote:
> Hi all, > > First question: > According to documentation, hfile.block.cache.size is by default 40 > percentage of maximum heap (-Xmx setting). If -Xmx is not used and only > -Xms is used, what will it be in this case? > > Second question: > This 40% heap space is shared by all entities (stores). How much block > cache is used by each store (entity)? Is it allocated on demand? If a > region has never been read after the region server is up, will block cache > be allocated for it? > The block cache stores blocks, which are chunks of an HFile, and are by default around 64KB in size. Allocation is on-demand. Learn more here http://hbase.apache.org/book.html#block.cache > > Third question: > Is it possible to tell from .META when a region was last read? If so, how? > > Many thanks, > > Linlin > > > > >
