There were good questions. I checked the user manual on their website, but didn’t find an answer to the big question: size of USB flash drive relative to disk to be cloned. Here is the interaction with their tech support, which was very quick. I’m writing while there is still 6 days to install after ordering your $100+/1TB USB flash drive.
Me: “How large a USB flash drive is required? My Windows C: drive is the whole of my 1TB SSD. It is 75% full, i.e., about 750GB. When doing a backup which clones the whole disk with another program the file produced is almost 600GB.
You say that my whole system will be cloned to the USB flash drive. Does that mean I need a 1TB USB flash drive? Can an external USB SSD or hard drive be used? Can a small USB flash drive be used for Flashboot and save data to a second external device to be read by Flashboot when booting and/or restoring?”
Flashboot_Support: ” Free space on drive C: does not take space on the cloned USB storage device, so 750GB will be definitely enough.
Further optimization depends on the type of clone: if this is an installable clone, it is always compressed. Average compression ratio is about 55%, 0.55*750GB = 412GB. That’s on average, actual ratio for your case depends on the amount of uncompressible data (like video/audio), 600GB corresponds to compression ratio of 80% (I’d call that realistic estimation for worst case). Anyway, if it does not fit, you can set an option in FlashBoot Pro to skip some files or folders during cloning (e.g. a specific folder or a few folders with large amount of uncompressible data).
Bootable clones, in theory, can be compressed too, but they work better uncompressed. Compressed bootable clones sometimes throw INACCESSIBLE_BOOT_DEVICE BSoD at boot time if cloned WIM file contains too many small internal files and amount of RAM is not sufficient to store the index. Uncompressed bootable clones are not affected by this problem. So for bootable clones USB capacity requirement is higher. 750GB if you don’t want to skip any data when making a bootable clone. Again, if it doesn’t fit, there’s always option to skip something not strictly necessary for bootable OS on a USB storage device (e.g. a large video archive).
Other types of USB storage devices besides USB thumbdrives are fine for FlashBoot. USB-SSD, USB-HDD, USB converter to MicroSD card — everything will do.
Regarding splitting of FlashBoot-related code (Windows reinstaller) on a bootable USB storage device and cloned WIM data on a separate non-bootble USB storage device: with FlashBoot, this is not possible. But overhead is negligible: for bootable clones, there is no overhead at all (no Windows reinstaller); and for installable clones overhead of Windows reinstaller is 0.2-0.5 GB depending on Windows version (0.2 Gb for Windows 7 and 0.5 Gb for Windows 11).”