Before memcached had a monotonic clock people would end up with immortal objects (underflowed TTL's) because ntp would start after memcached and make a huge adjustment due to the hardware clock being really off.

With the restart code, people could run a kernel upgrade and reboot while the daemon is down... so if this ends up causing a huge clock adjustment you're screwed.

And the more granular the time-based caching is within that system the more likely that mine time skew can kill cache.

I've had distributed systems perform unreliably in the < 30s range even with ntpupdate syncing in place.