Most UNIX systems store time as "seconds from the epoch, according to UTC". The advantage is that you can always assume that 1 day = 86400 seconds. The disadvan

Most UNIX systems store time as "seconds from the epoch, according to UTC". The advantage is that you can always assume that 1 day = 86400 seconds. The disadvantage is that the time is affected by leap seconds. The same-numbered POSIX second can be repeated twice in a row. Spanner instead deals with it by changing the length of the second. If you're assuming time intervals are accurate to the second, or that times are monotonic, have you actually reconfigured your system to use TAI?