Running Hadoop 0.22 and I need to restart the namenode so my new rack
configuration will be set into place. I am thinking of doing a quick stop
and start of the namenode but what will happen to the current clients? Can
they tolerate a 30 second hiccup by retrying?

--
--- Get your facts first, then you can distort them as you please.--

Hi Rita,

What kind of client you have?? Please be sure that there is no job running
and especially no data is copying while you do the restart.
Also are you restarting by using stop-dfs.sh and start-dfs.sh?

Regards,
Abhishek

On Thu, Jun 7, 2012 at 3:29 AM, Rita <[EMAIL PROTECTED]> wrote:

> Running Hadoop 0.22 and I need to restart the namenode so my new rack
> configuration will be set into place. I am thinking of doing a quick stop
> and start of the namenode but what will happen to the current clients? Can
> they tolerate a 30 second hiccup by retrying?
>
> --
> --- Get your facts first, then you can distort them as you please.--
>

Clients can't currently handle NN restarts gracefully. At least on my
1.x/0.20.x tests, the client didn't fail if it didn't had a new block
to allocate (when the NN was being restarted, since it didn't make a
connection to the NN at all) but it did fail when it was writing small
blocks very fast and the NN ended the connection when it was trying to
locate the next block (al)location to write to. So, don't bet on it,
and instead use HA NameNodes with failover, available in 2.x onwards.

On Thu, Jun 7, 2012 at 3:59 PM, Rita <[EMAIL PROTECTED]> wrote:
> Running Hadoop 0.22 and I need to restart the namenode so my new rack
> configuration will be set into place. I am thinking of doing a quick stop
> and start of the namenode but what will happen to the current clients? Can
> they tolerate a 30 second hiccup by retrying?
>
> --
> --- Get your facts first, then you can distort them as you please.--

--
Harsh J

This depends on what your clients are doing with HDFS and how they handle it
being unavailable.

-----Original Message-----
From: Rita [mailto:[EMAIL PROTECTED]]
Sent: Thursday, June 07, 2012 3:30 AM
To: <[EMAIL PROTECTED]>
Subject: namenode restart

Running Hadoop 0.22 and I need to restart the namenode so my new rack
configuration will be set into place. I am thinking of doing a quick stop
and start of the namenode but what will happen to the current clients? Can
they tolerate a 30 second hiccup by retrying?

--
--- Get your facts first, then you can distort them as you please.--