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From Anthony F <afc...@gmail.com>
Subject Re: data loss around splits when tserver goes down
Date Sun, 26 Jan 2014 21:47:57 GMT
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 <josh.elser@gmail.com> 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 accumulo.apache.org 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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