by CwF » 2020-03-05 15:24
Sure.
Yes, I do use an extra storage drive for image storage, a drive under debian control. My method is to image to this storage drive, and then image to a device from that storage drive. Then all the advantages are available.
You may have already made typical choices that make my method hard. Primarily, excessively large everything partitions. Since both OS's can link to extra storage, mount a drive under a folder, etc, I always keep the booting partition small. So there is a bunch of how-to in there, before we get to back up or migration strategies. There are many things to do to clean up an installation, I'll skip all that.
If you have the WIN 500GB almost full, then the qcow2 would be almost that big, and take a few hours, and maybe not be worth it. It would take a change in your ways to use this, but would save the agony once you need to move your 3GB WIN drive to something even bigger next time, kill that pattern NOW!
IF - you get the boot portion of your windows down to a manageable size, then the image (qcow2) you make and store on the debian drive (or supplementary drive) is a transient and a backup. At any time you can write that out to a new device. You can keep more than one, and you can back it up to a backup qcow2 at any time. I even have a second debian that can mount that storage disk to backup the debian in the same way. I keep a few spare SSD's and rotate them, so a known good is always offline.
The 'DATA' is all separate, and can use the technique. I have 'data sets' that are within many gigs, so I use qcow2 as their format, another method that will confuse people, so I'll skip that too.
If you intend to stay at 2 spinners only, and will replace the 500 with a 3TB, I assume you intend to dd to the 3GB and then expand to fill it. Typical, straight forward, and I wouldn't do it. It will complicate your future. I would consider the space you have, the number of sata(?) ports you have, and consider trying to get the OS's onto two SSD's. If you have room for the two spinners still, great, use them as storage only maybe one linked for each OS.
I'm skipping around, may be confusing, so bottom line. I use no other backup or image software ever, they're superfluous. To me, ssd's and disk are cheap, get a few extras.
+1 for keeping the OS's on separate drives. Multiboot single drives are only for laptop people. who can't make up their minds.
My largest debians are 120GB, non compressible LVM LUKS, a common ssd size. My windows images are smaller, 30GB and compress to ~18GB, so I have a few dupes, a good thing. My debians I use for vm's and can write to a device for OS or hardware testing, are 8.4GB full size, compressed to 1.3+ GB. Very easy to manage. On average I have more disk offline than on, another bonus.