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https://issues.apache.org/jira/browse/HBASE-5128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13199955#comment-13199955
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Jonathan Hsieh commented on HBASE-5128:
---------------------------------------
Update:
Recently found a case that may have been suffering from parent region not
getting removed by the catalog janitor. Since we rely on hdfs being ground
truth and this version did not check have offline/split status in meta, this
resulted in the tool attempting to merge all regions into one mega region.
Harsh mentioned, that the parent region cleanup issue might be related to
(HBASE-4799) (target cluster didn't have this patch).
Next cuts will add some failsafes -- specifiers to repair only specific tables
and to skip if a merge attempts to merge more than a specified number of
regions into one region.
Also, at the moment, I also have first cut versions that for 0.92/trunk but
have one flaky test.
> [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: 0.90.5, 0.92.0
> Reporter: Jonathan Hsieh
> Assignee: Jonathan Hsieh
>
> 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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