Hi Mickey, I would strongly suggest to setup a NTP server on your site - this is not really a big deal and with some tutorials on the net done quickly. Then configure your cassandra nodes (and all the rest if you like) to use your ntp instead of public ones. As I have learned the hard way - cassandra is not really happy when nodes have different times in some cases.
Benefit of this is, that your nodes will keep time in sync even without connection to the internet. Of course "your time" may drift without a proper timesource or connection but all nodes will have the same drift and so no problems with consistency. If your ntp syncs your nodes will be adjusted smoothly. Pro(?)-solution (what I did before): Attach a gps mouse to your ntp server and use that as time source. So you can have synchronized _and_ accurate time without any connection to public ntp servers as the gps satellites are flying atom clocks :) Just my 2 cents, Jan Von meinem iPhone gesendet > Am 31.03.2016 um 03:07 schrieb Mukil Kesavan <weirdbluelig...@gmail.com>: > > Hi, > > We run a 3 server cassandra cluster that is initially NTP synced to a single > physical server over LAN. This server does not have connectivity to the > internet for a few hours to sometimes even days. In this state we perform > some schema operations and reads/writes with QUORUM consistency. > > Later on, the physical server has connectivity to the internet and we > synchronize its time to an external NTP server on the internet. > > Are there any issues if this causes a huge time correction on the cassandra > cluster? I know that NTP gradually corrects the time on all the servers. I > just wanted to understand if there were any corner cases that will cause us > to lose data/schema updates when this happens. In particular, we seem to be > having some issues around missing secondary indices at the moment (not all > but some). > > Also, for our situation where we have to work with cassandra for a while > without internet connectivity, what is the preferred NTP architecture/steps > that have worked for you in the field? > > Thanks, > Micky
