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From Josh Elser <josh.el...@gmail.com>
Subject Re: Accumulo rolling restart
Date Fri, 17 Jan 2014 03:35:59 GMT
On Thu, Jan 16, 2014 at 10:00 PM, Vikram Srivastava
<vikrams@cloudera.com> wrote:
> Thanks for the replies. Couple of follow up questions -
> 1. What would the client experience during safe shutdown? Both a new client
> trying to read a tablet on the TServer going down, and an existing client
> reading a table on the TServer that's going down.

Existing client would talk to master to figure out the new assignment.
New client would do the same. Both would poll the master waiting for
the new assignment.

> 2. The reason I wanted to know about a method for controlled re-assignment
> while both TServers are running is so that I can bring the tablets back to
> the original TServer, thereby ensuring that each tablet is unavailable only
> once during the entire rolling restart process. If there is no such method
> currently, I'd be happy to file a jira.

Multiple hostings for a tablet would be considered a critical bug --
it should never happen. Balancing of tablets across tservers is
something that the master is often doing. You shouldn't have to do
anything but ensure the processes are running,

>
>
> On Thu, Jan 16, 2014 at 6:21 PM, Eric Newton <eric.newton@gmail.com> wrote:
>
>> And here's the command to do it:
>>
>> $ bin/accumulo admin stop server[:port]
>>
>>
>> But recovery is pretty fast... killing tservers can be faster than doing an
>> orderly shutdown.
>>
>> With 1.4, if I was restarting nodes on several racks, I would kill the
>> loggers on a rack, flush all tables, and then restart all the tservers and
>> loggers on that rack.  Rinse and repeat.
>>
>> -Eric
>>
>>
>>
>> On Thu, Jan 16, 2014 at 9:09 PM, John Vines <vines@apache.org> wrote:
>>
>> > You can stop an individual tserver which will do a safe shutdown of it
>> and
>> > reassignment. However, this won't work between releases due to potential
>> > version changes.
>> >
>> > Sent from my phone, please pardon the typos and brevity.
>> > On Jan 16, 2014 8:47 PM, "Vikram Srivastava" <vikrams@cloudera.com>
>> wrote:
>> >
>> > > Hi,
>> > >
>> > > Is there a way to re-assign a tablet from one Tserver to another while
>> > both
>> > > are running, in a manner so as to cause minimum impact to client?
>> > >
>> > > My motivation for this is to use something that does that to do rolling
>> > > restart of TServers.
>> > >
>> > > Thanks,
>> > >
>> > > Vikram
>> > >
>> >
>>

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