Some customers ask why the 15 minutes interval limit for DFS replication and bandwidth throttling. This is determined by the way that the operation system stores the information of DFS replication.
The DFS Replication schedule is stored as a binary attribute of size 336 bytes (2*24*7) which represents a schedule for a week. Each hour is represented in two bytes. Every hour is divided into four quarters, each of which occupies four bits, hence the 15 minutes interval:
[...] [...] [...] [...]
0 14 15 29 30 44 45 59
The four bits of a quarter takes 16 value ranges from 0X0, which indicates schedule is OFF, to 0xF, which indicates an ON schedule with full bandwidth. The levels in between defines an ON schedule with different levels of bandwidth.