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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-15314) Allow more than one backing file in bucketcache
Date Thu, 16 Mar 2017 11:02:42 GMT

     [ https://issues.apache.org/jira/browse/HBASE-15314?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

ramkrishna.s.vasudevan updated HBASE-15314:
       Resolution: Fixed
         Assignee: chunhui shen  (was: Aaron Tokhy)
     Hadoop Flags: Reviewed
    Fix Version/s: 2.0
     Release Note:   (was: The following patch adds a couple of features without making any
big changes to the existing BucketCache allocator. This approach introduces the notion of
'segmentation' (or in other words, the underlying IOEngine can be made up of non-contiguous
segments. Two methods are added to expose this information to the BucketCache allocator.

 boolean IOEngine#isSegmented()
 boolean IOEngine#doesAllocationCrossSegments(long offset, long len)

BucketCache calls these methods to determine if a 'contiguous' allocation of a particular
block size can occur. It does this by checking if doesAllocationCrossSegments(offset, len)
is true. If an allocation crosses a segment, another call to allocate is made for the same
block. The first block is wasted (it is marked allocated). The worst case is 1 'largest block'
per file. If an allocation fails for any reason, all/any allocated blocks (including wasted
ones) are freed again for subsequent allocation requests. This is very similar to a 'JBOD'
configuration (there is no striping of any kind).

To configure HBase to use multiple files when configuring the HBase bucket cache, set the
following configurations in hbase-site.xml:


/mnt/disk1, /mnt/disk2, /mnt/disk3 and /mnt/disk4 are expected to be separate filesystems
(one mountpoint per volume).  HBase would need to have read/write permissions to these directories.
 In this configuration, 4 sparsely allocated 256GB files (each named 'bucketcache') are created
in each directory on HBase RegionServer startup.  Ideally such a configuration is useful when
the underlying HBase filesystem is non-local.
           Status: Resolved  (was: Patch Available)

Pushed to master. Thanks for all the your efforts [~zyork] and @aaron
Thanks for the patch [~zjushch].
Thanks for the reviews.
Can you update the release note with the latest change? If not let me know I will try to phrase

> Allow more than one backing file in bucketcache
> -----------------------------------------------
>                 Key: HBASE-15314
>                 URL: https://issues.apache.org/jira/browse/HBASE-15314
>             Project: HBase
>          Issue Type: Sub-task
>          Components: BucketCache
>            Reporter: stack
>            Assignee: chunhui shen
>             Fix For: 2.0
>         Attachments: FileIOEngine.java, HBASE-15314.master.001.patch, HBASE-15314.master.001.patch,
HBASE-15314.patch, HBASE-15314-v2.patch, HBASE-15314-v3.patch, HBASE-15314-v4.patch, HBASE-15314-v5.patch,
HBASE-15314-v6.patch, HBASE-15314-v7.patch, HBASE-15314-v8.patch
> Allow bucketcache use more than just one backing file: e.g. chassis has more than one
SSD in it.

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