how to size bandwidth required for snapmirror?

[danielang]

i have a few windows servers and i need it to know the block level changed on each server for the bandwidth required. may i know what counters i need to turn on inside windows perfmon?

[radek_kubka]

Hi,

I don't think you can easily collect any hard numbers re block-level changes from a Windows server. One method I can think of is to install OSSV agents on all Windows servers & do OSSV backups to a NetApp filer.

Other than that, you are left with rules of thumbs, estimations & dark art :

- block-level changes are typically ~10x smaller than file-level changes

- block-level changes for file shares are typically <1% per day

- block-level changes for databases could be 20% per day or more

Regards,

Radek