Date: Thu, 30 Dec 2010 16:24:54 +1100 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Chris Brennan <xaero@xaerolimit.net> Cc: freebsd-questions@freebsd.org Subject: Re: a new hard-drive in a 2y/o laptop Message-ID: <20101230133126.O36121@sola.nimnet.asn.au> In-Reply-To: <20101229120038.3DFB0106591A@hub.freebsd.org> References: <20101229120038.3DFB0106591A@hub.freebsd.org>
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In freebsd-questions Digest, Vol 343, Issue 5, Message: 10
On Tue, 28 Dec 2010 11:02:45 -0500 Chris Brennan <xaero@xaerolimit.net> wrote:
> On Tue, Dec 28, 2010 at 2:23 AM, Michael Powell <nightrecon@hotmail.com>wrote:
>
> > Try zeroing out the mbr:
> >
> > Boot a LiveFS CD, then at a root prompt do:
> >
> > sysctl kern.geom.debugflags=16 and:
> >
> > dd if=/dev/zero of=/dev/adx oseek=1 bs=512 count=1
> >
> > where x equals your drive number. This will zero out any old MBR.
Er, no, Mike. The MBR is in sector 0 of the disk; that would zero out
sector 1 as oseek=1 skips over sector 0. What's in sector 1 depends on
how/whether the disk is sliced. In a 'dangerously dedicated' (unsliced)
disk like a memory stick perhaps, this would usually be /boot/boot1 and
include the bsdlabel. In a sliced disk, sectors 1 to 62 are typically
unused, the first slice usually starting at sector 63.
t23% fdisk -s ad0
/dev/ad0: 232581 cyl 16 hd 63 sec
Part Start Size Type Flags
1: 63 8385867 0x0b 0x00
2: 8385930 125821080 0xa5 0x80
3: 134207010 33543342 0xa5 0x00
4: 167750730 66685815 0xa5 0x00
If you really want to zero out sector 0, leave out the oseek (or use
oseek=0) - but you're better off using 'fdisk -Bi' to init a new disk.
> > I have seen this exact error before, and this is what took care of it.
> >
> > -Mike
Mmm .. it's not clear from Chris' original message exactly what he did.
> Mike,
>
> Thanks for that little tip, I tried it this morning and it hung for about 30
> second w/ no cd/hd activity, then it resumed w/ a beep, it printed some
> garbage on the console, the only ledgeable was the following
>
> [..]
> <GARBAGE>Invalid partition tableError loading operating systemMissing
> operating system<GARBAGE><GARBAGE><GARBAGE>1+0 records in
> 1+0 records out
> 512 bytes transferred in 2.712151 secs (189 bytes/sec)
> [..]
This doesn't make sense. Rather than 'I tried it' please show the exact
command/s you are issuing. Given it's a new disk you can afford to make
mistakes, but once you have anything valuable on a disk you need to take
extreme care with dd(1), it's so easy to fatfinger something wrong.
eg, what you show above would indicate just what you'd get by running:
dd if=/dev/ad4 count=1
ie, using 'if=' not 'of=', with of=/dev/stdout implied, ie to console.
If you do want to look at one or more raw sectors, it's very much safer
piping dd's stdout to hd (hexdump), as the delays and beep you mention
are consistent with piping raw bytes out to the console .. often this
can blow your console settings away (I've done it too many times :)
If you initialise a disk with the default MBR (or it came that way) then
that's usually what's in /boot/mbr - or /boot/boot0 if you've chosen the
FreeBSD boot manager, or something else if using (say) grub.
t23% dd if=/boot/mbr | hd
00000000 fc 31 c0 8e c0 8e d8 8e d0 bc 00 7c be 1a 7c bf |.1.........|..|.|
00000010 1a 06 b9 e6 01 f3 a4 e9 00 8a 31 f6 bb be 07 b1 |..........1.....|
00000020 04 38 2f 74 08 7f 75 85 f6 75 71 89 de 80 c3 10 |.8/t..u..uq.....|
00000030 e2 ef 85 f6 75 02 cd 18 80 fa 80 72 0b 8a 36 75 |....u......r..6u|
00000040 04 80 c6 80 38 f2 72 02 8a 14 89 e7 8a 74 01 8b |....8.r......t..|
00000050 4c 02 bb 00 7c f6 06 bd 07 80 74 2d 51 53 bb aa |L...|.....t-QS..|
00000060 55 b4 41 cd 13 72 20 81 fb 55 aa 75 1a f6 c1 01 |U.A..r ..U.u....|
00000070 74 15 5b 66 6a 00 66 ff 74 08 06 53 6a 01 6a 10 |t.[fj.f.t..Sj.j.|
00000080 89 e6 b8 00 42 eb 05 5b 59 b8 01 02 cd 13 89 fc |....B..[Y.......|
00000090 72 0f 81 bf fe 01 55 aa 75 0c ff e3 be b9 06 eb |r.....U.u.......|
000000a0 11 be d1 06 eb 0c be f0 06 eb 07 bb 07 00 b4 0e |................|
000000b0 cd 10 ac 84 c0 75 f4 eb fe 49 6e 76 61 6c 69 64 |.....u...Invalid|
000000c0 20 70 61 72 74 69 74 69 6f 6e 20 74 61 62 6c 65 | partition table|
000000d0 00 45 72 72 6f 72 20 6c 6f 61 64 69 6e 67 20 6f |.Error loading o|
000000e0 70 65 72 61 74 69 6e 67 20 73 79 73 74 65 6d 00 |perating system.|
000000f0 4d 69 73 73 69 6e 67 20 6f 70 65 72 61 74 69 6e |Missing operatin|
00000100 67 20 73 79 73 74 65 6d 00 90 90 90 90 90 90 90 |g system........|
00000110 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 |................|
*
000001b0 90 90 90 90 90 90 90 90 90 90 90 90 90 80 00 00 |................|
000001c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200
1+0 records in
1+0 records out
512 bytes transferred in 0.079548 secs (6436 bytes/sec)
Look familiar? :) That's what 'dd if=/dev/ad4 count=1 | hd' would show
on a disk with default MBR, except there'd be the slice data in the MBR
section of the boot sector, starting at 0x1be, ending with 'sig' 55aa.
> Restarting the install process, again accepting defaults, I am again
Again, please be more explicit. Defaults for what? One slice covering
the whole disk might be assumed for the disk slicing part of sysinstall
(fdisk-like wrapper) but assuming can be unsafe re disk setup, eg:
Disk name: ad0 FDISK Partition Editor
DISK Geometry: 232581 cyls/16 heads/63 sectors = 234441648 sectors (114473MB)
Offset Size(MB) End Name PType Desc Subtype Flags
0 0 62 - 12 unused 0
63 4094 8385929 ad0s1 7 fat 11
8385930 61436 134207009 ad0s2 8 freebsd 165
134207010 16378 167750351 ad0s3 8 freebsd 165
167750352 0 167750729 - 12 unused 0
167750730 32561 234436544 ad0s4 8 freebsd 165
234436545 2 234441647 - 12 unused 0
That's from 7.4-PRERELEASE sysinstall, if it matters (8.2-PRE is on s4)
And/or do you mean default sizes for labelling a FreeBSD slice, ie what
creates the slice's bsdlabel with sizes and mountpoints / /var /usr etc?
> 'Unable to find device node for /dev/ad4s1b in dev!
> The creation of filesystems will be aborted.'
> <OK>
/dev/ad4s1b is or should be the swap partition. Did you allocate swap?
Twice your memory size or larger? Way too much left to guesswork here,
but from that it rather looks like you may not have allocated any swap?
> My question is this now, could this be the fact that this is a really large
> drive and the bios is 'freaking' out (for lack of a better term) and not
> properly presenting the disk to the system? While I don't think this is
> something to consider, something in the back of my head suggests it is. The
Start worrying when you get near 2TB, when you'll _have_ to use gpart :)
> disk is a different spindle-speed then the old one.
>
> [..]
> 250G -> 5400RPM
> 750G -> 7200RPM
It should run about a third faster for sequential i/o, is all.
> maybe a (stab in the dark here) bus translation issue, disk is giving the
> bus too much information? *shrug I dunno, I'm babeling now and I don't have
> an obnoxious fish in my ear :(.
I don't expect this to be anything like that. Please show a) how many
slices you allocated and how big this FreeBSD slice is and b) how you
partitioned the FreeBSD slice into (and sizes of) / /var/ /usr [/tmp?]
and especially swap.
I wouldn't allocate any less than 1GB for your root (/) partition esp.
if building custom kernel/s; maybe that's fixed in sysinstall for 8.2?
cheers, Ian (please cc me on any reply; I take -questions as a digest)
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