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From "jiraposter@reviews.apache.org (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5128) [uber hbck] Enable hbck to automatically repair table integrity problems as well as region consistency problems while online.
Date Sat, 14 Jan 2012 00:16:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13186013#comment-13186013

jiraposter@reviews.apache.org commented on HBASE-5128:

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    I think '.META.' should be used.


    Should read 'that it was assigned to'


    Should read 'repairs require hbase ...'
    'to' at the end is not needed.


    This is about fixing region assignment, right ?
    Better include that in javadoc.


    Should read ' and correct '


    Would regionInfoMap be a better name ?


    Please correct this sentence's syntax.


    We should impose maximum number of iterations for the loop, right ?


    Should read 'method requires cluster to be online ...'


    Should read ' to be consistent'


    The method is called Repair, so the return value should be number of errors fixed, right
    I think a Pair return value would allow both errors detected and errors fixed to be returned.


    Should be called checkAndFixConsistency()


    Should be called checkAndFixIntegrity()


    This sentence can be omitted.
    If you keep it, please move it after the @return line.

- Ted

On 2012-01-13 22:49:33, jmhsieh wrote:
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/3435/
bq.  -----------------------------------------------------------
bq.  (Updated 2012-01-13 22:49:33)
bq.  Review request for hbase, Todd Lipcon, Ted Yu, Michael Stack, and Jean-Daniel Cryans.
bq.  Summary
bq.  -------
bq.  I'm posting a preliminary version that I'm currently testing on real clusters. The tests
are flakey on the 0.90 branch (so there is something async that I didn't synchronize properly),
and there are a few more TODO's I want to knock out before this is ready for full review to
be considered for committing. It's got some problems I need some advice figuring out.
bq.  Problem 1:
bq.  In the unit tests, I have a few cases where I fabricate new regions and try to force
the overlapping regions to be closed. For some of these, I cannot delete a table after it
is repaired without causing subsequent tests to fail. I think this is due to a few things:
bq.  1) The disable table handler uses in-memory assignment manager state while delete uses
in META assignment information.
bq.  2) Currently I'm using the sneaky closeRegion that purposely doesn't go through the master
and in turn doesn't modify in-memory state – disable uses out of date in-memory region assignments.
If I use the unassign method sends RIT transitions to the master, but which ends up attempting
to assign it again, causing timing/transient states.
bq.  What is a good way to clear the HMaster's assignment manager's assignment data for particular
regions or to force it to re-read from META? (without modifying the 0.90 HBase's it is meant
to repair).
bq.  Problem 2:
bq.  Sometimes test fail reporting HOLE_IN_REGION_CHAIN and SERVER_DOES_NOT_MATCH_META. This
means the old and new regions are confiused with each other and basically something is still
happening asynchronously. I think this is the new region is being assigned and is still transitioning.
Sound about right? To make the unit test deterministic, should hbck wait for these to settle
or should just the unit test wait?
bq.  This addresses bug HBASE-5128.
bq.      https://issues.apache.org/jira/browse/HBASE-5128
bq.  Diffs
bq.  -----
bq.    src/main/java/org/apache/hadoop/hbase/ipc/HMasterInterface.java c56b3a6 
bq.    src/main/java/org/apache/hadoop/hbase/master/AssignmentManager.java 330a7cc 
bq.    src/main/java/org/apache/hadoop/hbase/master/HMaster.java 3c7b68d 
bq.    src/main/java/org/apache/hadoop/hbase/util/HBaseFsck.java 6d3401d 
bq.    src/main/java/org/apache/hadoop/hbase/util/HBaseFsckRepair.java a3d8b8b 
bq.    src/main/java/org/apache/hadoop/hbase/util/hbck/OfflineMetaRepair.java 29e8bb2 
bq.    src/main/java/org/apache/hadoop/hbase/util/hbck/TableIntegrityErrorHandler.java PRE-CREATION

bq.    src/test/java/org/apache/hadoop/hbase/util/TestHBaseFsck.java a640d57 
bq.    src/test/java/org/apache/hadoop/hbase/util/hbck/HbckTestingUtil.java dbb97f8 
bq.    src/test/java/org/apache/hadoop/hbase/util/hbck/TestOfflineMetaRebuildBase.java 3e8729d

bq.    src/test/java/org/apache/hadoop/hbase/util/hbck/TestOfflineMetaRebuildHole.java 11a1151

bq.    src/test/java/org/apache/hadoop/hbase/util/hbck/TestOfflineMetaRebuildOverlap.java
bq.  Diff: https://reviews.apache.org/r/3435/diff
bq.  Testing
bq.  -------
bq.  All unit tests pass sometimes.  Some fail sometimes (generally the cases that fabricate
new regions).  
bq.  Not ready for commit.
bq.  Thanks,
bq.  jmhsieh

> [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
>            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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