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From Jerry Lam <chiling...@gmail.com>
Subject Re: WAL corruption
Date Mon, 02 Jul 2012 17:45:52 GMT
my understanding is that the WAL log is used for replication as well. 
If all your data has been persisted to disk (i.e. all data in memstores have been flushed
to disks) and replication is disabled, I believe you can delete the WAL without data loss.

just my 2 cents 

On 2012-07-02, at 1:37 PM, Bryan Keller wrote:

> During an upgrade of my cluster to 0.90 to 0.92 over the weekend, the WAL (files in the
/hbase/.logs directory) was corrupted and it prevented HBase from starting up. The exact exception
was "java.io.IOException: Could not obtain the last block locations" on the WAL files.
> I was able to recover by deleting the /hbase/.logs directory. My question is, if HBase
had no pending updates, i.e. nothing writing to it, is there any risk of data loss by deleting
the WAL directory? For example, does rebalancing, flushing, or compaction use the WAL or is
the WAL used only for inserts/updates/deletes?

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