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On Tue, Dec 13, 2016 at 1:25 PM, Anuj Wadehra <anujw_2...@yahoo.co.in> wrote: > Any NTP experts willing to take up these questions? > > Thanks > Anuj > > On Sun, 27 Nov, 2016 at 12:52 AM, Anuj Wadehra > <anujw_2...@yahoo.co.in> wrote: > Hi, > > One popular NTP setup recommended for Cassandra users is described at > Thankshttps://blog.logentries.com/2014/03/synchronizing-clocks-in-a-cassandra-cluster-pt-2-solutions/ > . > > Summary of article is: > Setup recommends a dedicated pool of internal NTP servers which are > associated as peers to provide a HA NTP service. Cassandra nodes sync to > this dedicated pool but define one internal NTP server as preferred server > to ensure relative clock synchronization. Internal NTP servers sync to > external NTP servers. > > My questions: > > 1. If my ISP provider is providing me a pool of reliable NTP servers, should > I setup my own internal servers anyway or can I sync Cassandra nodes > directly to the ISP provided servers and select one of the servers as > preferred for relative clock synchronization? > > > I agree. If you have to rely on public NTP pool which selects random servers > for sync, having an internal NTP server pool is justified for getting tight > relative sync as described in the blog > > 2. As per my understanding, peer association is ONLY for backup scenario . > If a peer loses time synchronization source, then other peers can be used > for time synchronization. Thus providing a HA service. But when everything > is ok (happy path), does defining NTP servers synced from different sources > as peers lead them to converge time as mentioned in some forums? > > e.g. if A and B are peers and thier times are 9:00:00 and 9:00:10 after > syncing with respective time sources, then will they converge their clocks > as 9:00:05? > > I doubt the above claim regarding time converge. Also no formal doc says > that. Comments? > > > Thanks > Anuj >
