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HBase, mail # user - hbase time skew


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Re: hbase time skew
Ted Yu 2013-03-16, 00:07
When a region server reports to master the first time, ServerManager does
the following check:

   * Checks if the clock skew between the server and the master. If the
clock skew exceeds the

   * configured max, it will throw an exception; if it exceeds the
configured warning threshold,

   * it will log a warning but start normally.
The unit is in milliseconds.
These two parameters are configurable.

Please take a look at the source code if possible - the code should come
with tar ball.

Cheers

On Fri, Mar 15, 2013 at 4:50 PM, <[EMAIL PROTECTED]> wrote:

>  Hi Ted,
>
> For the source code below, what's the unit of 30000? Is the maxSkew 30
> seconds?  Also, what does Hbase do when the time skew exeeds 10 seconds and
> 30 seconds? Are these two values configurable?
>
> Thanks,
>
> YuLing
> >maxSkew = c.getLong("hbase.master.maxclockskew", 30000);
> >     warningSkew = c.getLong("hbase.master.warningclockskew", 10000);
> > ./src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
>
>
> -----Original Message-----
> From: Ted Yu [mailto:[EMAIL PROTECTED]]
> Sent: Friday, March 15, 2013 4:28 PM
> To: [EMAIL PROTECTED]
> Subject: Re: hbase time skew
>
> Please upgrade to 0.94.5, if possible.
>
> There have been a lot of bug fixes and performance improvements since
> 0.94.1.
>
> On Fri, Mar 15, 2013 at 4:26 PM, <[EMAIL PROTECTED]> wrote:
>
> > Yes, I'm using 0.94.1.
> >
> > -----Original Message-----
> > From: Ted Yu [mailto:[EMAIL PROTECTED]]
> > Sent: Friday, March 15, 2013 3:53 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: hbase time skew
> >
> > Are you using 0.94.x ?
> >
> > If so, see the following:
> >
> >     maxSkew = c.getLong("hbase.master.maxclockskew", 30000);
> >     warningSkew = c.getLong("hbase.master.warningclockskew", 10000);
> > ./src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
> >
> > Cheers
> >
> > On Fri, Mar 15, 2013 at 3:49 PM, <[EMAIL PROTECTED]> wrote:
> >
> > > Hi,
> > >
> > > We recently encountered the issue that HBase tables got into a state
> > > that was not disabled nor enabled. We found that the root cause was
> > > the linux clock skewed more than 5 hours. I googled and understood
> > > that hbase can only  handle about a couple of seconds time skew. We
> > > were wondering if there's any configuration in HBase that we can do
> > > so as to increase the number of seconds that hbase could handle?
> > >
> > > Thanks very much,
> > >
> > > YuLing
> > >
> >
>