Re: Undo MBR
On Thu, Sep 04, 2003 at 05:58:38PM -0400 or thereabouts, Paul Murphy wrote: > On Thu, 4 Sep 2003 17:38:04 -0400 > > Matthew Seaman <[EMAIL PROTECTED]> wrote: > > > Errr... That's a little excessive. The quick way to remove the > > > FreeBSd boot manager and restore a standard MBR is: > > > > > > # boot0cfg -B -b /boot/mbr ad0 > > > > > > (The OP might want to do that on his data disk ad2 as well). No > > > changes to the filesystems on those disks should be necessary. > > > > > > > THAT'S what I was looking for! I knew it should have something to do > > with boot0cfg, just didn't read the man page closely enough I guess. > > > > Hmm, problems... > > # boot0cfg -B -b /boot/mbr ad0 > # boot0cfg: /boot/mbr: unknown or incompatible boot code You need # fdisk -B -b /boot/mbr ad0 -- Josh ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: Undo MBR
On Thu, 4 Sep 2003 17:38:04 -0400 Paul Murphy <[EMAIL PROTECTED]> wrote: > On Thu, 4 Sep 2003 13:11:25 +0100 > Matthew Seaman <[EMAIL PROTECTED]> wrote: > > > On Wed, Sep 03, 2003 at 06:00:30PM -0500, David Kelly wrote: > > > On Wednesday 03 September 2003 05:13 pm, Paul Murphy wrote: > > > > I have just installed FBSD-CURRENT on a test box. During > > > > install I > > > > unwittingly installed a BootMgr entry for the second HDD (it > > > > will just be a data disk, no need to boot from it). > > > > > > > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this > > > > "erase" > > > > the BootMgr or will I have to redo Fdisk and etcetera. There is > > > > no data on the disk yet so this would be no hardship, but is > > > > there a"proper" way of doing what I want? > > > > > > > > > > > > Just to clarify, upon booting I get: > > > > > > > > F1 FreeBSD > > > > F5 Drive 1 > > > > > > > > but I just want to boot straight into FreeBSD, no "dual-boot". > > > > > > I don't know why you are fretting about this prompt and > > > momentarily pause in the boot process. Also think you are confused > > > about the MBR thing on the 2nd drive. > > > > > > The prompt above is coming from your first HD. If the BIOS did not > > > know about the 2nd drive the F5 entry would not be there and the > > > FreeBSD F1 entry would still be there. You could hide this prompt > > > by retuning the MBR to pause 0 or 1 seconds. Zero might be > > > infinite. > > > > > > To eliminate the prompt, wipe the HD and reinstall "dangerously > > > dedicated." The result will be a disk which lacks the headers > > > which allows other x86 OS's to understand what/how the disk is > > > used. > > > > Errr... That's a little excessive. The quick way to remove the > > FreeBSd boot manager and restore a standard MBR is: > > > > # boot0cfg -B -b /boot/mbr ad0 > > > > (The OP might want to do that on his data disk ad2 as well). No > > changes to the filesystems on those disks should be necessary. > > > > THAT'S what I was looking for! I knew it should have something to do > with boot0cfg, just didn't read the man page closely enough I guess. > Hmm, problems... # boot0cfg -B -b /boot/mbr ad0 # boot0cfg: /boot/mbr: unknown or incompatible boot code Now, a little bit of history: This is a new install if FBSD-CURRENT from binaries, after which I realized I shouldn't have installed BootMgr. Then I tried to 'undo' it but having no success I did the email thing. _Meanwhile_ I did a CVS upgrade to FBSD-HEAD (for unrelated problems). I shouldn't think this would cause the boot0cfg error though. The /boot/mbr file is pretty stable code isn't it? -- Cogeco ergo sum pgp0.pgp Description: PGP signature
Re: Undo MBR
On Thu, 4 Sep 2003 13:11:25 +0100 Matthew Seaman <[EMAIL PROTECTED]> wrote: > On Wed, Sep 03, 2003 at 06:00:30PM -0500, David Kelly wrote: > > On Wednesday 03 September 2003 05:13 pm, Paul Murphy wrote: > > > I have just installed FBSD-CURRENT on a test box. During install > > > I > > > unwittingly installed a BootMgr entry for the second HDD (it will > > > just be a data disk, no need to boot from it). > > > > > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this "erase" > > > the BootMgr or will I have to redo Fdisk and etcetera. There is no > > > data on the disk yet so this would be no hardship, but is there a > > > "proper" way of doing what I want? > > > > > > > > > Just to clarify, upon booting I get: > > > > > > F1 FreeBSD > > > F5 Drive 1 > > > > > > but I just want to boot straight into FreeBSD, no "dual-boot". > > > > I don't know why you are fretting about this prompt and momentarily > > pause in the boot process. Also think you are confused about the MBR > > thing on the 2nd drive. > > > > The prompt above is coming from your first HD. If the BIOS did not > > know about the 2nd drive the F5 entry would not be there and the > > FreeBSD F1 entry would still be there. You could hide this prompt by > > retuning the MBR to pause 0 or 1 seconds. Zero might be infinite. > > > > To eliminate the prompt, wipe the HD and reinstall "dangerously > > dedicated." The result will be a disk which lacks the headers which > > allows other x86 OS's to understand what/how the disk is used. > > Errr... That's a little excessive. The quick way to remove the > FreeBSd boot manager and restore a standard MBR is: > > # boot0cfg -B -b /boot/mbr ad0 > > (The OP might want to do that on his data disk ad2 as well). No > changes to the filesystems on those disks should be necessary. > THAT'S what I was looking for! I knew it should have something to do with boot0cfg, just didn't read the man page closely enough I guess. -- Cogeco ergo sum pgp0.pgp Description: PGP signature
Re: Undo MBR
Thanks for the replies. > I have just installed FBSD-CURRENT on a test box. During install I [etc] > So, if there is nothing to be lost, just try it out and see what > happens. Smoke testing is a tried and true technique. Nothing ventured, nothing gained! > You kind of have to read the disklabel man page in conjunction with > the fdisk man page to make any sense of things, and then it may still > take some experimenting. Yes I think that's where I got my previous command line from (or someplace similar) although the example I read said 'count=15' vs. 'count=32' > If you have a bootable DOS disk with fdisk, you can clear the MBR > without destroying partitions by executing: > > fdisk /mbr I did know that, I just wanted to do it The FreeBSD Way(tm). > corresponding switches/parameters, but the questioner said there was > nothing to save on the disk Yes > and wanted to wipe it, so... Not necessarily, if I could do it without (potentially) destroying any data, that would be the ideal solution (for future reference). -- Cogeco ergo sum pgp0.pgp Description: PGP signature
Re: Undo MBR
> > Actually, the first dd sometimes fails, if the disk has never had > > anything put on it. If so, just ignore it and go on with the fdisk. > > > > jerry > > If you have a bootable DOS disk with fdisk, you can clear the MBR without > destroying partitions by executing: > > fdisk /mbr You should be able to do something similar with FreeBSD fdisk and the corresponding switches/parameters, but the questioner said there was nothing to save on the disk and wanted to wipe it, so... jerry > > In my pre-FreeBSD days, I used to do this to clear LILO out after removing a > Linux installation so that it would boot to Windows. > > Best of luck, > > Andrew Gould > > > > ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: Undo MBR
On Thursday 04 September 2003 09:35 am, Jerry McAllister wrote: > Hi, > > > I have just installed FBSD-CURRENT on a test box. During install I > > unwittingly installed a BootMgr entry for the second HDD (it will > > just be a data disk, no need to boot from it). > > > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this "erase" the > > BootMgr or will I have to redo Fdisk and etcetera. There is no data > > on the disk yet so this would be no hardship, but is there a "proper" > > way of doing what I want? > > So, if there is nothing to be lost, just try it out and see what > happens. Smoke testing is a tried and true technique. > > Anyway, you really don't need to bother, but yes, that should wipe it. > There are some examples at the bottom of 'man disklabel' that you > might want to check out - even though you really are talking about > fdisk stuff. The fdisk man page is weak, for example it doesn't even > document the -I switch (tho it lists it at the top) which is what you want. > You kind of have to read the disklabel man page in conjunction with the > fdisk man page to make any sense of things, and then it may still take > some experimenting. > > From man disklabel: > >dd if=/dev/zero of=/dev/da0 bs=512 count=32 >fdisk -BI da0 >dd if=/dev/zero of=/dev/da0s1 bs=512 count=32 >disklabel -w -B da0s1 auto >disklabel -e da0s1 > > Completely wipe any prior information on the disk, creating a new > bootable disk with a DOS partition table containing one ``whole-disk'' > slice. Then initialize the slice, then edit it to your needs. The dd > commands are optional, but may be necessary for some BIOSes to > properly recognize the disk. > > Actually, the first dd sometimes fails, if the disk has never had > anything put on it. If so, just ignore it and go on with the fdisk. > > jerry If you have a bootable DOS disk with fdisk, you can clear the MBR without destroying partitions by executing: fdisk /mbr In my pre-FreeBSD days, I used to do this to clear LILO out after removing a Linux installation so that it would boot to Windows. Best of luck, Andrew Gould ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: Undo MBR
Hi, > I have just installed FBSD-CURRENT on a test box. During install I > unwittingly installed a BootMgr entry for the second HDD (it will > just be a data disk, no need to boot from it). > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this "erase" the > BootMgr or will I have to redo Fdisk and etcetera. There is no data > on the disk yet so this would be no hardship, but is there a "proper" > way of doing what I want? So, if there is nothing to be lost, just try it out and see what happens. Smoke testing is a tried and true technique. Anyway, you really don't need to bother, but yes, that should wipe it. There are some examples at the bottom of 'man disklabel' that you might want to check out - even though you really are talking about fdisk stuff. The fdisk man page is weak, for example it doesn't even document the -I switch (tho it lists it at the top) which is what you want. You kind of have to read the disklabel man page in conjunction with the fdisk man page to make any sense of things, and then it may still take some experimenting. >From man disklabel: dd if=/dev/zero of=/dev/da0 bs=512 count=32 fdisk -BI da0 dd if=/dev/zero of=/dev/da0s1 bs=512 count=32 disklabel -w -B da0s1 auto disklabel -e da0s1 Completely wipe any prior information on the disk, creating a new bootable disk with a DOS partition table containing one ``whole-disk'' slice. Then initialize the slice, then edit it to your needs. The dd commands are optional, but may be necessary for some BIOSes to properly recognize the disk. Actually, the first dd sometimes fails, if the disk has never had anything put on it. If so, just ignore it and go on with the fdisk. jerry ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: Undo MBR
On Wed, Sep 03, 2003 at 06:00:30PM -0500, David Kelly wrote: > On Wednesday 03 September 2003 05:13 pm, Paul Murphy wrote: > > I have just installed FBSD-CURRENT on a test box. During install I > > unwittingly installed a BootMgr entry for the second HDD (it will > > just be a data disk, no need to boot from it). > > > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this "erase" > > the BootMgr or will I have to redo Fdisk and etcetera. There is no > > data on the disk yet so this would be no hardship, but is there a > > "proper" way of doing what I want? > > > > > > Just to clarify, upon booting I get: > > > > F1 FreeBSD > > F5 Drive 1 > > > > but I just want to boot straight into FreeBSD, no "dual-boot". > > I don't know why you are fretting about this prompt and momentarily > pause in the boot process. Also think you are confused about the MBR > thing on the 2nd drive. > > The prompt above is coming from your first HD. If the BIOS did not know > about the 2nd drive the F5 entry would not be there and the FreeBSD F1 > entry would still be there. You could hide this prompt by retuning the > MBR to pause 0 or 1 seconds. Zero might be infinite. > > To eliminate the prompt, wipe the HD and reinstall "dangerously > dedicated." The result will be a disk which lacks the headers which > allows other x86 OS's to understand what/how the disk is used. Errr... That's a little excessive. The quick way to remove the FreeBSd boot manager and restore a standard MBR is: # boot0cfg -B -b /boot/mbr ad0 (The OP might want to do that on his data disk ad2 as well). No changes to the filesystems on those disks should be necessary. Cheers, Matthew -- Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way PGP: http://www.infracaninophile.co.uk/pgpkey Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK pgp0.pgp Description: PGP signature
Re: Undo MBR
On Wednesday 03 September 2003 05:13 pm, Paul Murphy wrote: > I have just installed FBSD-CURRENT on a test box. During install I > unwittingly installed a BootMgr entry for the second HDD (it will > just be a data disk, no need to boot from it). > > If I do 'dd if=/dev/zero of=/dev/rad2 count=15' will this "erase" > the BootMgr or will I have to redo Fdisk and etcetera. There is no > data on the disk yet so this would be no hardship, but is there a > "proper" way of doing what I want? > > > Just to clarify, upon booting I get: > > F1 FreeBSD > F5 Drive 1 > > but I just want to boot straight into FreeBSD, no "dual-boot". I don't know why you are fretting about this prompt and momentarily pause in the boot process. Also think you are confused about the MBR thing on the 2nd drive. The prompt above is coming from your first HD. If the BIOS did not know about the 2nd drive the F5 entry would not be there and the FreeBSD F1 entry would still be there. You could hide this prompt by retuning the MBR to pause 0 or 1 seconds. Zero might be infinite. To eliminate the prompt, wipe the HD and reinstall "dangerously dedicated." The result will be a disk which lacks the headers which allows other x86 OS's to understand what/how the disk is used. -- David Kelly N4HHE, [EMAIL PROTECTED] = The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
