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https://issues.apache.org/jira/browse/HBASE-5128?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Hsieh updated HBASE-5128:
----------------------------------
Release Note:
HBaseFsck (hbck) has been updated with new repair capabilities. hbck is a tool
for checking the region consistency and the table integrity invariants of a
running HBase cluster. Checking region consistency verifies 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 all possible
row keys resolve to exactly one region of a table -- e.g. there are no
individual degenerate or backwards regions; no holes between regions; and no
overlapping regions. Previously hbck had the ability to diagnose
inconsistencies but only had the ability to repair deployment region
consistency problems. The updated version now has been augmented with the
ability repair region consistency problems in .META. (by patching holes),
repair overlapping regions (via merging), patch region holes (by fabricating
new regions), and detecting and adopting orphaned regions (by fabricating new
.regioninfo file if it is missing in a region's dir).
Caveats:
* The new hbck selects repairs assuming that HDFS as ground truth, the previous
version treated .META. as ground truth.
* The hbck '-fix' option is present but deprecated and replaced with
-fixAssignments option.
* This tool adds APIs in 0.90.7, 0.92.2 and 0.94.0 for clean repairs. The 0.90
version of he tool is compatible with HBase 0.90+, but may require restarting
the master or individual individual regionserver for table
enable/disable/delete commands to work properly.
Updated release notes.
> [uber hbck] Online automated repair of table integrity and region consistency
> problems
> --------------------------------------------------------------------------------------
>
> 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, 0.94.0, 0.96.0
> Reporter: Jonathan Hsieh
> Assignee: Jonathan Hsieh
> Fix For: 0.90.7, 0.92.2, 0.94.0, 0.96.0
>
> Attachments: 5128-trunk.addendum, hbase-5128-0.90-v2.patch,
> hbase-5128-0.90-v2b.patch, hbase-5128-0.90-v4.patch,
> hbase-5128-0.92-v2.patch, hbase-5128-0.92-v4.patch, hbase-5128-0.94-v2.patch,
> hbase-5128-0.94-v4.patch, hbase-5128-trunk-v2.patch, hbase-5128-trunk.patch,
> hbase-5128-v3.patch, hbase-5128-v4.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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