Index: src/main/docbkx/book.xml =================================================================== --- src/main/docbkx/book.xml (revision 1510848) +++ src/main/docbkx/book.xml (working copy) @@ -1524,7 +1524,34 @@ +
+ Experimental Bucket Cache + BucketCache is another implementation of BlockCache which supports big block cache for high performance and would greatly decrease CMS and heap fragmentation in JVM caused by read activities. + It will manage blocks' storage position through Bucket Allocator, the cached blocks could be stored in the memory or file system. + Bucket Cache could be used as a mainly block cache(see the CombinedBlockCache source), + which is combined with LruBlockCache to decrease CMS and fragment by GC. + BucketCache also could be used as a secondary cache(e.g. using Fusionio to store block) to enlarge cache space.Here are two use cases: + + + Use bucket cache as main memory cache, configured as the following: + + "hbase.bucketcache.ioengine" "heap" + "hbase.bucketcache.size" 0.4 (size for bucket cache, 0.4 is a percentage of max heap size) + + + + + Use bucket cache as a secondary cache, configured as the following: + + "hbase.bucketcache.ioengine" "file:/disk1/hbase/cache.data"(The file path where to store the block data) + "hbase.bucketcache.size" 1024 (size for bucket cache, unit is MB, so 1024 means 1GB) + "hbase.bucketcache.combinedcache.enabled" false (default value being true) + + + + Use at your own risk. See more additional information on this new https://issues.apache.org/jira/secure/attachment/12562209/Introduction%20of%20Bucket%20Cache.pdf
+
Write Ahead Log (WAL)