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From Arshak Navruzyan <arsh...@gmail.com>
Subject Re: documentation regarding WAL
Date Sat, 18 Jan 2014 03:45:27 GMT
I assume we want the docs to reflect the latest(and/or moving forward)
behavior.

I'll make the changes and submit a patch.
On Jan 17, 2014 5:15 PM, "Keith Turner" <keith@deenlo.com> wrote:

> The documentation is out of date for 1.5.  Its ok for 1.4.
>
> In 1.4 tservers write to logger servers which write to local disk.
>  Starting in 1.5 tservers write their WALs directly to HDFS.
>
> In 1.4 and1.5 the master will coordinate sorting of logs for recovery
> purposes.  In 1.4 loggers do the sorting.  In 1.5 tservers do the sorting.
>  In both versions the sorted logs are stored in HDFS.
>
>
> On Fri, Jan 17, 2014 at 6:53 PM, Arshak Navruzyan <arshakn@gmail.com>wrote:
>
>> I am wondering whether the following sections of the docs correctly
>> describe the current WAL behavior or are these remnants of the time when
>> the WAL was stored locally.
>>
>> *2.8. Fault-Tolerance*
>>
>> The Master will coordinate the copying of write-ahead logs to HDFS so the
>> logs are available to all tablet servers.
>>  *11.10. Recovery*
>> Recovery is performed by asking the loggers to copy their write-ahead
>> logs into HDFS. As the logs are copied, they are also sorted, so that
>> tablets can easily find their missing updates. The copy/sort status of each
>> file is displayed on Accumulo monitor status page.
>>
>>
>> are these accurate or does each tserver directly write it's WAL to HDFS
>> (vs. having to copy it)?
>>
>>
>>
>>
>>
>>
>

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