Mike,

Thanks for the quick response.  It was very helpful and what I expected.

Thanks for the link to the zookeeper failure docs.

Long story short, we decided to go to 1.7.3 for now and then look at 1.8.1 in a 
couple months after it has a little more soak time.  The only reason for the 
rollback test was in case our production upgrade has any issues.

Again thanks for the quick reply.

Bob

Robert Rosekrans
iNovex Information Systems
Analytic Portfolio Tech Lead
(C) 410-303-9144
(W) 410-379-5311

From: Michael Wall [mailto:mjw...@gmail.com]
Sent: Tuesday, June 06, 2017 8:42 AM
To: dev@accumulo.apache.org; u...@accumulo.apache.org
Cc: Rosekrans, Robert (US N-INOVEX INFORMATION SYSTEMS INC.) 
<robert.rosekr...@lmco.com>
Subject: EXTERNAL: Re: Accumulo upgrade rollback...

Hi Bob,

Unfortunately, rolling back an upgraded system is not an automated task.  
Moving from 1.5.4 to 1.6.6 as you saw !METADATA changed to accumulo.metadata 
and accumulo.root.  The upgrade also changes the data version of the rfiles, so 
any new files written from mutations or compactions will not be readable by 
prior versions.  Good for you that you saved off the /accumulo directory in 
HDFS.

What you are going to need to do is reinitialize Accumulo, create the tables 
with whatever splits and configs you need, then bulk import the rfiles from 
your /accumulo_backup directory in the new tables.  That will make the metadata 
and zookeeper happy.  You can follow the directions for a Zookeeper failure at 
http://accumulo.apache.org/1.8/accumulo_user_manual.html#zookeeper_failure.

Interested in what you are seeing that made you want to rollback.  If you are 
testing, you may want to try upgrading to the latest 1.8, which is currently 
1.8.1.

Let us know how it goes.

Mike



On Tue, Jun 6, 2017 at 2:25 AM Robert Rosekrans 
<robert.rosekr...@inovexcorp.com<mailto:robert.rosekr...@inovexcorp.com>> wrote:

Accumulo team,

Our team is upgrading from Accumulo 1.5.4 to 1.6.6 then to 1.7.3.  We are 
testing the upgrade in our integration environment. Before we started the 
upgrade, we copied our HDFS /accumulo directory to /accumulo_backup. My hope 
was that I could just swap out the directories to rollback. However when I did, 
the metadata table didn't load. I looked at the tables and the metadata table 
was listed as "metadata" versus "!METADATA" indicating it was using the new 
format of the tables.  My guess is that zookeeper is maintaining the previous 
upgraded table names.

My question is what is the easiest way to rollback the data.

Thanks
Bob


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