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On old sysVR4 i will format floppies as so

1.44 MB floppy

mkfs -F ufs /dev/dsk/f03ht 2560  

1.2MB Floppy

mkfs -F ufs /dev/dsk/f13dt 2440

The 2440 and 2560 are calculated with 512*4 and 512*5 In your opinion how to calculate the correct value for 2.88MB floppy? Thanks

The block is 5760 as reported by manual,unix version is interactive unix 4.1 the error given is this

mkfs -L  -f /dev/rdsk/f0q36dt  5760:900  1 72
bytes per logical block = 1024
total logical blocks = 2880
total inodes = 896
gap (physical blocks) = 1
cylinder size (physical blocks) = 72 
mkfs: write error: 9
  • What do you understand by "old SysV"? As Svr4 is the latest, this must be Svr3 or older, but these versions do not support ufs. – schily Sep 21 '15 at 18:27
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    Maybe you could do dd if=/dev/dsk/fwhatever of=/dev/null while the 2.88 diskette is in the drive, and see how many (complete, not partial) blocks dd reports copying successfully. – Mark Plotnick Sep 21 '15 at 18:49
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Are you sure about your figure? I was thinking that a 1.44MB floppy was a disk composed by 80 tracks, each track containing 18 sectors of 512 bytes and that you can write on the two sides. The 1.2MB got only 15 tracks. So based on this logic, you have (80 * 18 * 2) == 2880 sectors on 1.44MB floppy and (80 * 15 * 2) == 2400 on 1.2MB floppy. I'm not sure if you have to calculate yourself the overhead introduced by UFS file system (boot sector, superblock ...) or if mkfs make the calculation for you but based on this logic, since a 2.88MB floppy seems to be composed by 80 tracks of 36 sectors each and you can write two faces, it makes you (80 * 36 * 2) == 5760 blocks of 512 bytes. Assuming you have to provide to mkfs the whole size of the filesystem you want to create (and not only the usable size) I will use:

mkfs -F ufs /dev/yourdisk 5760
  • Answer is correct,on manual i see this line ` / et c /mkfs /dev/dsk/ f 0q3 6dt 5 7 6 0 : 9 0 0 1 7 2 ` where 5760 is total blocks 900 inodes 1 gap rotational and 72 is block per cylinder size but give me error – elbarna Sep 22 '15 at 12:03

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