a little more info might help. but i have formatted my drives several times, i have a cecha o1 60 GB launch, backwards compatible Phat console. and have never lost the cfw. formatted drives on 3.55kmeaw and after i upgraded to rogero 4.21.. never had a problem, just re installed multiman and went from there. hope this helps
If you have NAND (old CECHA-CECHG phats), you won't loose the CFW if u format the hdd because it's fully stored on 2x 128MB NAND chips. If you have NOR (newer than CECHG), then only part of the FW is stored on the NOR Chip (16MB) and the rest is stored on you HDD. So you have to re-install the FW when you format/replace the HDD.
Now, if you have an older version of Rogero 4.30 (v1.xx), you cannot re-install it if you format the HDD. So upgrade to v2.05 before you format. If you're on Rebug, you can format an re-install the CFW without any problems.