Hi Tim,

   I believe that it runs into an issue which is specific to cloudera release 
we fixed recently. For details, could you discuss it in cdh forum?
Copy me(h...@cloudera.com <mailto:h...@cloudera.com>) in the forum so I can 
explain more there.


> On Oct 12, 2016, at 8:13 AM, Ted Yu <yuzhih...@gmail.com> wrote:
> Have you looked at HBASE-16578 ?
> Cheers
>> On Oct 12, 2016, at 8:02 AM, Tim Robertson <timrobertson...@gmail.com> wrote:
>> Hi devs,
>> [Had a quick chat with Lars G. about this and before opening a Jira I
>> thought I'd raise it here first]
>> We have just experienced data loss in HBase 1.0.0-cdh5.4.10.
>> Before I dig into this further, I'd like to just ask if anyone has seen
>> this before?
>> The initial state was a table (tim_test) built with MOB support and a few
>> 10's million rows and 10's billions of cells.
>> I wanted to rename the table to get this into production and did so as
>> follows:
>> snapshot 'tim_test', 'tim_test-snapshot'
>> clone_snapshot 'tim_test-snapshot', 'prod_b_map'
>> At this stage the application all looked good, and so I continued with:
>> delete_snapshot 'tim_test-snapshot'
>> disable 'tim_test'
>> drop ‘tim_test’
>> Then things went... awry and data just started dropping out in the app.
>> Before long, all MOB data seemingly is gone.
>> The references in the new table MOB folder appear to point to the source
>> table (e.g.
>> /hbase/mobdir/data/default/prod_b_map/ba42a2e8e9b669d9fc85bdfeed2f5f2a/EPSG_4326/tim_test=14bf5f1737ac65c34615ed97c0b7de06-d41d8cd98f00b204e9800998ecf8427e20161006ff8baa70d21f408caefe8ae6318dfba2).
>> The RS logs full of ERROR like:
>> 2016-10-12 15:19:14,640 ERROR org.apache.hadoop.hbase.regionserver.HStore:
>> The mob file
>> d41d8cd98f00b204e9800998ecf8427e20161006b59865f80e604781a79ebfa2ddd66b48
>> could not be found in the locations
>> [hdfs://ha-nn/hbase/mobdir/data/default/tim_test/14bf5f1737ac65c34615ed97c0b7de06/EPSG_4326,
>> hdfs://ha-nn/hbase/archive/data/default/tim_test/14bf5f1737ac65c34615ed97c0b7de06/EPSG_4326]
>> What I don't know is:
>> 1) was this running a background task to copy the MOB data when the
>> snapshot was cloned and I just deleted the source before the copy was
>> complete?
>> - or
>> 2) when running "snapshot and clone" it just references the source MOB
>> data until a (?) change?
>> 3) snapshot and clone just doesn't support MOB?
>> Can anyone shed some light on this easily before I dig into it please?
>> While this situation exists (at least in 1.0.0) might it be good to get
>> info about data loss for MOB tables into the snapshot clone docs?
>> Thanks,
>> Tim

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