Nameservers are part of the basic infrastructure of the internet, translating names like www.software.coop into numbers like 18.104.22.168. You really don’t want them to be completely unreachable because it breaks lots of things, so as well as the primary nameserver, it’s good to have secondary ones, both in the same hosting facility (for fast replacement if the primary fails) and a different city (for fallback if the hosting facility or its network fails).
Since moving one of our customer’s secondary nameservers to an OpenVZ virtual server in another city last year, it’s been having serious stability problems. That server ran MyDNS as its main brain, but the primary servers are an unholy mishmash of BIND, MyDNS and I don’t know what else (they’re not all ours), so domain updates are done by periodic AXFR requests.
Every so often, mydns would quit with an “out of memory” error, which was narrowed down to a few possibilities on the mailing list. I tried pretty much everything that was suggested (mostly off-list), but we still didn’t have a stable nameserver.
Since then, MyDNS-NG has taken up development and Howard Wilkinson has worked to cure some of the memory leaks. I’ve upgraded to 22.214.171.124 and this time, the nameserver is still running so far. The out of memory problem was random, so I’ll leave it a few more days before sending reports and thank-yous upstream, but I’m pretty damn happy about this.