Bryan Beaudreault created HBASE-27579:
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Summary: CatalogJanitor can cause data loss due to errors during
cleanMergeRegion
Key: HBASE-27579
URL: https://issues.apache.org/jira/browse/HBASE-27579
Project: HBase
Issue Type: Bug
Reporter: Bryan Beaudreault
In CatalogJanitor.cleanMergeRegion, there is the following check:
{code:java}
HRegionFileSystem regionFs = null;
try {
regionFs =
HRegionFileSystem.openRegionFromFileSystem(this.services.getConfiguration(), fs,
tabledir, mergedRegion, true);
} catch (IOException e) {
LOG.warn("Merged region does not exist: " + mergedRegion.getEncodedName());
}
if (regionFs == null || !regionFs.hasReferences(htd)) {
.. do the cleanup ..
} {code}
I think the assumption here is that an IOException would only be thrown if a
region doesn't exist? We had a very poorly timed NameNode failover, during
CatalogJanitor run, after a merge. The NameNode failover caused the
openRegionFromFileSystem call to fail, which logged:
{code:java}
WARN org.apache.hadoop.hbase.master.janitor.CatalogJanitor: Merged region does
not exist: 32c71224852c5a4b94a3ba271b4fcb15 {code}
This region did in fact exist and had not fully compacted, so there were still
some lingering reference files.
The cleanup process moves the parent regions to the archive directory, but the
default TTL for those files in the archive directory is only 5 minutes. After
that they are cleaned up and the data is now unrecoverable.
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