I've got a server with a LOT of small files -- many millions files, and over 1.5 TB of data. I need a decent backup strategy.


Any filesystem-based backup takes too long -- just enumerating which files need to be copied takes a day. 
Acronis can do a disk image in 24 hours, but fails when it tries to do a differential backup the next day. 
DFS-R won't replicate a volume with this many files.


I'm starting to look at Double Take, which seems to be able to do continuous replication. Are there other solutions that can do continuous replication at a block or sector level -- not file-by-file over a WAN?

Some details:


The files are split up into about 75,000 directories.
99% of the daily change comes from adding new directories; existing files are rarely changed.


There's some other relevant discussion here.


Question: Increasing voltage source frequency
Answer: You can change the frequency by making changes in either time or frequency. As you mentioned that you have changed time to 0.5ms, please make sure whether you have changed time period of one complete cycle (on time + off time). If your time period of one complete cycle is 0.5ms, your frequency should be 2khz, because frequency is number of cycles per second.