gnu@l5.uucp (John Gilmore) (12/05/85)
In article <100@hadron.UUCP>, jsdy@hadron.UUCP (Joseph S. D. Yao) writes: > For BSD, the root partition is always 15884 sectors ("blocks" is > not a good term here, although the code uses it). This is nice > and reasonable for an RP0[456]. It is minimal for the others. > Being LCD, it is thus the standard. This will usually not completely > cover a cylinder on other drives, leading to problems when dd'ing > using a multiple of the cylinder size. Partition B, often used > as swap, is 33440 sectors long. Hmm, I always wondered where those numbers came from. On my Sun-3: # dkinfo sd0 sd0: SCSI controller at addr 200000, unit # 0 1022 cylinders 8 heads (base 2) 17 sectors/track a: 15884 sectors (116 cyls, 6 tracks, 6 sectors) starting cylinder 0 b: 33440 sectors (245 cyls, 7 tracks, 1 sectors) starting cylinder 117 c: 138448 sectors (1018 cyls) starting cylinder 0 g: 89080 sectors (655 cyls) starting cylinder 363 :-) !!! PPS: I repartitioned the other drives though, so they use whole cylinders.
jsdy@hadron.UUCP (Joseph S. D. Yao) (12/06/85)
In article <317@l5.uucp> gnu@l5.uucp (John Gilmore) writes: >In article <100@hadron.UUCP>, jsdy@hadron.UUCP (Joseph S. D. Yao) writes: >> For BSD, the root partition is always 15884 sectors ... This is nice >> and reasonable for an RP0[456]. ... Partition B, often used >> as swap, is 33440 sectors long. >Hmm, I always wondered where those numbers came from. ... From /etc/disktab: rp06|RP06|DEC RP06:\ :ty=removable:ns#22:nt#19:nc#815:\ :pa#15884:ba#8192:fa#1024:\ :pb#33440:pc#340670:\ ... :ph#291346:bh#4096:fh#1024: (actually, no longer true) (because they drop 3 tracks) (for bad block information.) 19 sectors/track, 418 sectors/cylinder. 38 * 418 = 15884 80 * 418 = 33440 697 * 418 = 291346 === 815 Oddly enough, rm03|RM03|DEC RM03:\ :ty=removable:ns#32:nt#5:nc#823:\ :pa#15884:ba#8192:fa#1024:\ :pb#33440:pc#131680:\ 32 sectors/track, 160 sectors/cylinder. 209 * 160 = 33440 rm05|RM05|DEC RM05:\ :ty=removable:ns#32:nt#19:nc#823:\ :pa#15884:ba#8192:fa#1024:\ :pb#33440:pc#500384:\ 32 sectors/track, 608 sectors/cylinder. 55 * 608 = 33440 But nothing else fits. ;-) -- Joe Yao hadron!jsdy@seismo.{CSS.GOV,ARPA,UUCP}