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From Mikael Sitruk <mikael.sit...@gmail.com>
Subject Re: ANN: The third hbase 0.94.0 release candidate is available for download
Date Fri, 11 May 2012 10:24:36 GMT
Stack hi

Sorry for not being precise enough.
The point is that i'm trying to check the impact of HA scenarios. one of
them is when the master goes down.
That is true that the Master is not it the critical path of read/write
unless (please correct me if i'm wrong):
1. new client are trying to connect
2. split/merge occurs
3. another node fails.
So in case the master goes down and start back, i'm interested to
understand how long of unavailability the system will be (under the
scenario above)

For the second case where a RS is down, there is certainly impact on
performance/latency since now other RS need to handle the region of the RS
that is down.
Again i'm interested to understand the impact on performance/latency of the
system under failure of a component and for get/put and scan.

I hope it is clearer and make sense to you.
BTW if you have such graph can you post them??


On Fri, May 11, 2012 at 8:18 AM, Stack <stack@duboce.net> wrote:

> On Thu, May 10, 2012 at 10:04 PM, Mikael Sitruk <mikael.sitruk@gmail.com>
> wrote:
> > Stack do you have latency graph during the time the RS and HMaster were
> > down? (did you see a big variance in latency)?
> Not sure I follow Mikael.  The master is not in the read/write path so
> its restart wouldn't impinge on latency.
> If you are asking about the cluster restart underneath the mapreduce
> job, yes, latency went off the charts since no reads were being served
> while the cluster being rebooted.
> (Pardon me if I am misunderstanding your question)
> > BTW this test is a MR/scan test or you also have update and delete?
> >
> Its just a scan (via gora).
> I have not done evaluation beyond what I described.  What would you
> like to see Mikael?
> St.Ack

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