Date: Tue, 29 Aug 1995 11:44:35 -0700 (PDT) From: Julian Elischer <julian@ref.tfs.com> To: luigi@labinfo.iet.unipi.it (Luigi Rizzo) Cc: hackers@freebsd.org Subject: Re: fdisk & disklabel troubles Message-ID: <199508291844.LAA17364@ref.tfs.com> In-Reply-To: <199508290749.JAA04925@labinfo.iet.unipi.it> from "Luigi Rizzo" at Aug 29, 95 09:49:29 am
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OK I originally hacked fdisk together from the MACH utility "DISKUTIL" > > After spending a few hours on the above programs, I have more > details which I hope somebody can clarify. I am starting with a > fresh, full 950726-SNAPSHOT installation on wd0 (entire disk for > freebsd) and an aborted install on wd2 (entire disk for freebsd, > but just did the partition and newfs). > > I see that: > > * fdisk cannot read a valid partition table from either disk. The > "bios idea" of the disk, as printed by fdisk, shows one cylinder less > than the real size. seems to work here? below, I add a third slice to take up the 31 sectors that dos left before itself. I then dump out the slices, and see that the new slice is in fact added to the disk.. jules: {8} ./fdisk -u /dev/rwd0 ******* Working on device /dev/rwd0 ******* parameters extracted from in-core disklabel are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) parameters to be used for BIOS calculations are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) Do you want to change our idea of what BIOS thinks ? [n] n Note: BIOS sector numbering always starts with sector 1 Information from DOS bootblock is: The data for partition 0 is: sysid 4,(Primary DOS with 16 bit FAT) start 32, size 49888 (24 Meg), flag 0 beg: cyl 0/ sector 1/ head 1; end: cyl 119/ sector 32/ head 12 Do you want to change it? [n] n The data for partition 1 is: sysid 165,(FreeBSD/NetBSD/386BSD) start 49920, size 359840 (175 Meg), flag 80 beg: cyl 120/ sector 1/ head 0; end: cyl 984/ sector 32/ head 12 Do you want to change it? [n] n The data for partition 2 is: <UNUSED> Do you want to change it? [n] y Supply a decimal value for "sysid" [0] 165 Supply a decimal value for "start" [0] 1 Supply a decimal value for "size" [0] 31 Explicitly specifiy beg/end address ? [n] n sysid 165,(FreeBSD/NetBSD/386BSD) start 1, size 31 (0 Meg), flag 0 beg: cyl 0/ sector 2/ head 0; end: cyl 0/ sector 32/ head 0 Are we happy with this entry? [n] y The data for partition 3 is: <UNUSED> Do you want to change it? [n] Do you want to change the active partition? [n] We haven't changed the partition table yet. This is your last chance. parameters extracted from in-core disklabel are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) parameters to be used for BIOS calculations are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) Information from DOS bootblock is: 0: sysid 4,(Primary DOS with 16 bit FAT) start 32, size 49888 (24 Meg), flag 0 beg: cyl 0/ sector 1/ head 1; end: cyl 119/ sector 32/ head 12 1: sysid 165,(FreeBSD/NetBSD/386BSD) start 49920, size 359840 (175 Meg), flag 80 beg: cyl 120/ sector 1/ head 0; end: cyl 984/ sector 32/ head 12 2: sysid 165,(FreeBSD/NetBSD/386BSD) start 1, size 31 (0 Meg), flag 0 beg: cyl 0/ sector 2/ head 0; end: cyl 0/ sector 32/ head 0 3: <UNUSED> Should we write new partition table? [n] y ioctl DIOCWLABEL: Operation not supported by device jules: {8} ./fdisk /dev/rwd0 ******* Working on device /dev/rwd0 ******* parameters extracted from in-core disklabel are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) parameters to be used for BIOS calculations are: cylinders=985 heads=13 sectors/track=32 (416 blks/cyl) Note: BIOS sector numbering always starts with sector 1 Information from DOS bootblock is: The data for partition 0 is: sysid 4,(Primary DOS with 16 bit FAT) start 32, size 49888 (24 Meg), flag 0 beg: cyl 0/ sector 1/ head 1; end: cyl 119/ sector 32/ head 12 The data for partition 1 is: sysid 165,(FreeBSD/NetBSD/386BSD) start 49920, size 359840 (175 Meg), flag 80 beg: cyl 120/ sector 1/ head 0; end: cyl 984/ sector 32/ head 12 The data for partition 2 is: sysid 165,(FreeBSD/NetBSD/386BSD) start 1, size 31 (0 Meg), flag 0 beg: cyl 0/ sector 2/ head 0; end: cyl 0/ sector 32/ head 0 The data for partition 3 is: <UNUSED> jules: {9} > > * fdisk cannot write the partition table either (or at least, it cannot > be read back!). I tried to set the correct parameters and write to > disk, fdisk did not write any error message but reading again the > partition table shows the same old values. > (cannot do further experiments with working fdisks, but my setting is > easily reproducible). see above getting ready: jules: {18} sh MAKEDEV wd0s3{a,b,c,d,e,f,g} > > > * (BTW, the "usage" line of fdisk shows a "-r" flag which does not > exist. hmmm mea culpa > > Luckily, fdisk does not kill the system. With disklabel, things seem to > be worse: whenever I try to write a label, the system reboots. > > As a reference, here are the different ideas of the disks: > > REAL: 1010 cyl, 12 hd, 55 sec, total 666.600 sectors > fdisk: 1009 cyl, 12 hd, 55 sec, part. start 1, size 665.939 > beg.: cyl.0 sec.2 hd.0 > end: cyl.1009 sec.1 hd.0 > disklabel: 1009 cyl, 12 hd, 55 sec, size 666.545 > > > REAL: 1057 cyl, 16 hd, 63 sec, total 1.065.456 sectors > fdisk: 1056 cyl, 16 hd, 63 sec, part. start 1, size 1.064.447 > beg.: cyl.0 sec.2 hd.0 > end: cyl.32 sec.1 hd.0 > disklabel: 1056 cyl, 16 hd, 63 sec, size 1.065.393 ok I'll try: I'll try put a label on the new little part I just made.. getting ready: jules: {18} sh MAKEDEV wd0s3{a,b,c,d,e,f,g} jules: {19} disklabel -R /dev/rwd0s3 /tmp/xxx hmmm yep, it hangs the system.... I guess I'll need to go have a look at that.. :)
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