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From Josh Elser <>
Subject Re: data loss around splits when tserver goes down
Date Sun, 26 Jan 2014 21:29:33 GMT
I meant to reply to your original email, but I didn't yet, sorry.

First off, if Accumulo is reporting that it found multiple locations for 
the same extent, this is a (very bad) bug in Accumulo. It might be worth 
looking at tickets that at marked as "affects 1.5.0" and "fixed in 
1.5.1" on Jira. It's likely that we've already encountered and fixed the 
issue, but, if you can't find a fix that was already made, we don't want 
to overlook the potential need for one.

For both "live" and "bulk" ingest, *neither* should lose any data. This 
is one thing that Accumulo should never be doing. If you have multiple 
locations for an extent, it seems plausible to me that you would run 
into data loss. However, you should focus on trying to determine why you 
keep running into multiple locations for a tablet.

After you take a look at Jira, I would likely go ahead and file a jira 
to track this since it's easier to follow than an email thread. Be sure 
to note if there is anything notable about your installation (did you 
download it directly from the site)? You should also 
include what OS and version and what Hadoop and ZooKeeper versions you 
are running.

On 1/26/2014 4:10 PM, Anthony F wrote:
> I have observed a loss of data when tservers fail during bulk ingest.
> The keys that are missing are right around the table's splits indicating
> that data was lost when a tserver died during a split.  I am using
> Accumulo 1.5.0.  At around the same time, I observe the master logging a
> message about "Found two locations for the same extent".  Can anyone
> shed light on this behavior?  Are tserver failures during bulk ingest
> supposed to be fault tolerant?

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