I/O on checkpoints (no replies)

Hello,

I am trying to understand the I/O performed by Innodb. Concretely, i would like to understand how checkpoints are performed at the file system level, i.e, how checkpoints start and how end. I already have seen that the info of the last checkpoint is stored on the ib_logfile0 file at the offset 512 or 1536 (alternately).

My questions are:
(1) Is this disk access (mentioned above) the last write of a checkpoint?
(2) How can i detect that a checkpoint is starting? It is a access on the ibdata file or .ibd?

I am doing this questions because i want to understand what are the data that i need to save during a checkpoint in order to doan incremental backup.

Thanks in advance,
Best regards,
Tiago