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From Anthony F <>
Subject Re: data loss around splits when tserver goes down
Date Mon, 27 Jan 2014 00:00:54 GMT
The stack trace is pretty close and the steps to reproduce match the
scenario in which I observed the issue.  But there's no fix (in Jira)
against 1.5.0, just 1.6.0.

On Sun, Jan 26, 2014 at 5:56 PM, Josh Elser <> wrote:

> Just because the error message is the same doesn't mean that the root
> cause is also the same.
> Without looking more into Eric's changes, I'm not sure if ACCUMULO-2057
> would also affect 1.5.0. We're usually pretty good about checking backwards
> when bugs are found in newer versions, but things slip through the cracks,
> too.
> On 1/26/2014 5:09 PM, Anthony F wrote:
>> This is pretty much the issue:
>> Slightly different error message but it's a different version.  Looks
>> like its fixed in 1.6.0.  I'll probably need to upgrade.
>> On Sun, Jan 26, 2014 at 4:47 PM, Anthony F <
>> <>> wrote:
>>     Thanks, I'll check Jira.  As for versions, Hadoop 2.2.0, Zk 3.4.5,
>>     CentOS 64bit (kernel 2.6.32-431.el6.x86_64).  Has much testing been
>>     done using Hadoop 2.2.0?  I tried Hadoop 2.0.0 (CDH 4.5.0) but ran
>>     into HDFS-5225/5031 which basically makes it a non-starter.
>>     On Sun, Jan 26, 2014 at 4:29 PM, Josh Elser <
>>     <>> wrote:
>>         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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