How does "RENTENTIVE" work in S7-1200?

Hello.

In the S7-1200 it is possible to set tags in a DB to be "retentive".
Such type memory can handle only a limited count of read and write cycles.

We have a counter that counts products.
This count value is kept in a global data block, which is set to retentive.
A 1,000,000 products are counted each day.

Is the limit of read/write cycles of the retentive memory effected?
Or is the retentive nature of the DB only used on power ON and power OFF?

Thank you for your attention.

I think the ram is backupped by flash memory which is only be written on powerloss (and read during boot). The internal power supply has a super capacitor which provides enough power for an orderly shutdown (e.g. write retentive memory). Probably this is the reason why the amount of retentive memory is limited.

Not entirly sure but this is how it could work.