About the Off-heap BucketCache
If the BucketCache is enabled, it stores data blocks, leaving the on-heap cache free for storing indexes and Bloom filters.
The physical location of the
BucketCache storage can be either in memory
(off-heap) or in a file stored in a fast disk.- Off-heap: This is the default configuration.
- File-based: You can use the file-based storage mode to store the
BucketCacheon an SSD or FusionIO device,
You can configure a column family to keep its data blocks in the L1
cache instead of the BucketCache, using the
HColumnDescriptor.cacheDataInL1(true) method or by
using the following syntax in HBase
Shell:hbase> alter 'myTable', CONFIGURATION => {CACHE_DATA_IN_L1 => 'true'}}