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Date: Tue, 3 Mar 2015 08:09:14 -0800
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 <CA+TL_nksHF1kbxjEQ0zp-fKS+BX1A6Sy14A9ewqd3LGc4gNr4A@mail.gmail.com>
Subject: Re: question about state transition
From: "vlad.gm@gmail.com" <vlad.gm@gmail.com>
To: user@helix.apache.org
Cc: Development@helix.apache.org
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We had the same issue. We created a state model like this:
Offline -> Bootstrap -> Slave -> Master

The heavy lifting is done in offline to bootstrap.

The model has a constraint of one simultaneous transition per partition and
we prioritize the transitions as follows:
Slave to master
Bootstrap to slave
Offline to bootstrap
All others

There is at most one master and one slave.

This will make the controller try to bring the higher ranked server all the
way to slave before issuing the command for the lower ranked server to go
to slave and then making the higher ranked server go to master. I  not sure
how to bridge the small gap without master, while keeping the single master
target.

Probably you could do without the bootstrap phase and do the heavy work in
offline to slave, while keeping the other constraints

Regards,
Vlad
On Mar 3, 2015 12:47 AM, "Gavin Li" <lyo.gavin@gmail.com> wrote:

> Hi,
>
> We have each server handle some partitions, and we use Master Slave model.
>
> We need to do some work when transit from offline to slave, sometimes it
> takes long time. So when the server ranked higher in ideal state is up and
> doing the work during the transition of offline to slave, the other server
> is changed to slave from master.
>
> This is causing some period of time that there's no master at all which is
> problematic. Is it possible to bring the other server down when the higher
> rank server is transiting from slave to master instead of when transition
> from offline to slave?
>
> THanks,
> Gavin Li
>

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<p dir=3D"ltr">We had the same issue. We created a state model like this:<b=
r>
Offline -&gt; Bootstrap -&gt; Slave -&gt; Master</p>
<p dir=3D"ltr">The heavy lifting is done in offline to bootstrap.</p>
<p dir=3D"ltr">The model has a constraint of one simultaneous transition pe=
r partition and we prioritize the transitions as follows:<br>
Slave to master<br>
Bootstrap to slave<br>
Offline to bootstrap<br>
All others</p>
<p dir=3D"ltr">There is at most one master and one slave.</p>
<p dir=3D"ltr">This will make the controller try to bring the higher ranked=
 server all the way to slave before issuing the command for the lower ranke=
d server to go to slave and then making the higher ranked server go to mast=
er. I=C2=A0 not sure how to bridge the small gap without master, while keep=
ing the single master target.</p>
<p dir=3D"ltr">Probably you could do without the bootstrap phase and do the=
 heavy work in offline to slave, while keeping the other constraints<br></p=
>
<p dir=3D"ltr">Regards,<br>
Vlad</p>
<div class=3D"gmail_quote">On Mar 3, 2015 12:47 AM, &quot;Gavin Li&quot; &l=
t;<a href=3D"mailto:lyo.gavin@gmail.com">lyo.gavin@gmail.com</a>&gt; wrote:=
<br type=3D"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:=
0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">Hi=
,<div><br></div><div>We have each server handle some partitions, and we use=
 Master Slave model.</div><div><br></div><div>We need to do some work when =
transit from offline to slave, sometimes it takes long time. So when the se=
rver ranked higher in ideal state is up and doing the work during the trans=
ition of offline to slave, the other server is changed to slave from master=
.</div><div><br></div><div>This is causing some period of time that there&#=
39;s no master at all which is problematic. Is it possible to bring the oth=
er server down when the higher rank server is transiting from slave to mast=
er instead of when transition from offline to slave?</div><div><br></div><d=
iv>THanks,</div><div>Gavin Li</div></div>
</blockquote></div>

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