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https://issues.apache.org/jira/browse/HBASE-5128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13182417#comment-13182417
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Jonathan Hsieh commented on HBASE-5128:
---------------------------------------
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.
Problem 1:
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:
1) The disable table handler uses in-memory assignment manager state while
delete uses in META assignment information.
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the master and in turn doesn't modify in-memory state -- disable uses out of
date in-memory region assignments.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.
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).
Problem 2:
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?
> [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
> 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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