Cassandra Cluster Synchronization


Cassandra is a highly-distributable NoSQL database with tunable consistency. What makes it highly distributable makes it also, in part, vulnerable: the whole deployment must run on synchronized clocks. It’s quite surprising that, given how crucial this is, it is not covered sufficiently in literature. And, if it is, it simply refers…

NTPd DOS attacks


Miscreants who earlier this week took down servers for League of Legends, EA.com, and other online game services used a never-before-seen technique that vastly amplified the amount of junk traffic directed at denial-of-service targets. Rather than directly flooding the targeted services with torrents of data, an attack group calling itself DERP Trolling…

Time Maps in Action


This shows a time map for a client (center) that is getting NTP time from a variety of standard internet NTP servers and via a customer site (to the left). A TimeKeeper Pocket GrandMaster (bottom left) is serving multiple Stratum servers within the Customer network and we are connecting our…

Time Synchronization in the Cloud


Synchronizing clocks in the cloud, especially for virtual machines, is way beyond the capabilities of ordinary synchronization methods. Tests show that virtual machines in the cloud relying on NTPd can fall off the reference time by tens of minutes over a single day. Even bare metal cloud platforms are significantly…

The business case for being time protocol agnostic.


Time Synchronization and Distribution is a business critical issue but it is easy to become bogged down in arcane technology/marketing controversies.  One of those controversies is over the choice between low level network protocols used to deliver time to application server computers.  The most widely used time synchronization protocol in…