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From "Jonathan Hsieh (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-5128) [uber hbck] Enable hbck to automatically repair table integrity problems as well as region consistency problems while online.
Date Sat, 10 Mar 2012 00:58:58 GMT

     [ https://issues.apache.org/jira/browse/HBASE-5128?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jonathan Hsieh updated HBASE-5128:
----------------------------------

    Affects Version/s: 0.96.0
                       0.94.0
               Status: Patch Available  (was: In Progress)

This version is getting very large, and though imperfect it is quite useful.  Would prefer
to get this in and then add follow in jiras to improve this. 

Attached version for trunk.  Will backport to 0.92/0.94.  Also have version for 0.90 but would
like to get trunk version in first now.
                
> [uber hbck] Enable hbck to automatically repair table integrity problems as well as region
consistency problems while online.
> -----------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5128
>                 URL: https://issues.apache.org/jira/browse/HBASE-5128
>             Project: HBase
>          Issue Type: New Feature
>          Components: hbck
>    Affects Versions: 0.92.0, 0.90.5, 0.94.0, 0.96.0
>            Reporter: Jonathan Hsieh
>            Assignee: Jonathan Hsieh
>         Attachments: hbase-5128-trunk.patch
>
>
> The current (0.90.5, 0.92.0rc2) versions of hbck detects most of region consistency and
table integrity invariant violations.  However with '-fix' it can only automatically repair
region consistency cases having to do with deployment problems.  This updated version should
be able to handle all cases (including a new orphan regiondir case).  When complete will likely
deprecate the OfflineMetaRepair tool and subsume several open META-hole related issue.
> Here's the approach (from the comment of at the top of the new version of the file).
> {code}
> /**
>  * HBaseFsck (hbck) is a tool for checking and repairing region consistency and
>  * table integrity.  
>  * 
>  * Region consistency checks verify that META, region deployment on
>  * region servers and the state of data in HDFS (.regioninfo files) all are in
>  * accordance. 
>  * 
>  * Table integrity checks verify that that all possible row keys can resolve to
>  * exactly one region of a table.  This means there are no individual degenerate
>  * or backwards regions; no holes between regions; and that there no overlapping
>  * regions. 
>  * 
>  * The general repair strategy works in these steps.
>  * 1) Repair Table Integrity on HDFS. (merge or fabricate regions)
>  * 2) Repair Region Consistency with META and assignments
>  * 
>  * For table integrity repairs, the tables their region directories are scanned
>  * for .regioninfo files.  Each table's integrity is then verified.  If there 
>  * are any orphan regions (regions with no .regioninfo files), or holes, new 
>  * regions are fabricated.  Backwards regions are sidelined as well as empty
>  * degenerate (endkey==startkey) regions.  If there are any overlapping regions,
>  * a new region is created and all data is merged into the new region.  
>  * 
>  * Table integrity repairs deal solely with HDFS and can be done offline -- the
>  * hbase region servers or master do not need to be running.  These phase can be
>  * use to completely reconstruct the META table in an offline fashion. 
>  * 
>  * Region consistency requires three conditions -- 1) valid .regioninfo file 
>  * present in an hdfs region dir,  2) valid row with .regioninfo data in META,
>  * and 3) a region is deployed only at the regionserver that is was assigned to.
>  * 
>  * Region consistency requires hbck to contact the HBase master and region
>  * servers, so the connect() must first be called successfully.  Much of the
>  * region consistency information is transient and less risky to repair.
>  */
> {code}

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