So, how about the time changes? Actually in our case, we only have one node. Let's say initially the customer does not install a NTP server and the clock becomes slow. Then the customer installs a new NTP server, the clock is adjusted by the NTP server, which ends up being advanced 5 mins. Would this 'sudden' clock change cause any issues? We tested on our test bed and found 5 hours advance of the clock would cause major issues. I'm not sure if it would be the same behavior if the clock is being advanced 3 ~ 5 mins?
Thanks, YuLing -----Original Message----- From: Michel Segel [mailto:michael_se...@hotmail.com] Sent: Monday, March 18, 2013 2:29 PM To: user@hbase.apache.org Subject: Re: hbase time skew The actual time isn't an issue. It's that all of the nodes in the cluster have the same time... Give or take a couple of ms. Sent from a remote device. Please excuse any typos... Mike Segel On Mar 18, 2013, at 2:39 PM, <yulin...@dell.com> wrote: > The problem is that in our case, the customer configures the NTP server and > it could be invalid. We're trying to cover user error cases, but on the other > hand we're trying to understand how big time skew hbase can handle... > > Thanks, > > YuLing > > -----Original Message----- > From: Kevin O'dell [mailto:kevin.od...@cloudera.com] > Sent: Saturday, March 16, 2013 5:49 AM > To: user@hbase.apache.org > Subject: Re: hbase time skew > > I am going to agree with Michael on this one. Don't change the clock skew, > fix it. > > On Fri, Mar 15, 2013 at 9:56 PM, Michel Segel <michael_se...@hotmail.com> > wrote: >> Create an ntp server local to the cluster? This will eliminate the skew in >> the first place. >> >> Sent from a remote device. Please excuse any typos... >> >> Mike Segel >> >> On Mar 15, 2013, at 3:53 PM, Ted Yu <yuzhih...@gmail.com> wrote: >> >>> 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, <yulin...@dell.com> 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 > > > > -- > Kevin O'Dell > Customer Operations Engineer, Cloudera >
