boot sector f*ed

[PJ]

Roland Smith wrote:
> On Thu, Aug 13, 2009 at 03:58:33PM -0400, PJ wrote:
>   
>> Roland Smith wrote:
>>     
>>> On Thu, Aug 13, 2009 at 09:53:06AM -0400, PJ wrote:
>>>   
>>>       
>>>> I apologize for the lengthy explanation below, but perhaps it will give
>>>> some insight on what is see from this end:
>>>>
>>>> Ok, I've had all night to (subliminally) think about all this and
>>>> actually, I am tending more toward problems in FreeBSD... (this is not
>>>> an apology or a defense of my lack of knowledge or capacities, just a
>>>> clarification so you know what kind of a dummy you're dealing with)
>>>> First, let me explain that everything that we have been talking about -
>>>> the recovery methods, installation, hardware problems, etc. are all
>>>> extremely, and I mean extremely, subject to an awful lot of variables.
>>>>     
>>>>         
>>> I don't understand?
>>>
>>> I must confess that I find your explanations sometimes a bit vague. You're
>>> sitting in front of the machine with the problems. We (on the mailing list)
>>> see only what you say. It is difficult for me at least to piece together what
>>> exactly happened.
>>>
>>> If you are reporting errors, try to be as specific as possible. E.g. don't say
>>> "I updated the machine and it doesn't boot anymore". Start with something like:
>>> "After running freebsd-update with the options blabla" or "after updating the
>>> machine from the 7.2 CD making the following choices...". And then say "I got
>>> stuck in the FreeBSD logo screen", or "I got stuck on a screen showing the
>>> lines 'Default: 0:ad(0,a)/boot/loader' and 'boot:'". That gives us at
>>> least a chance to see what has gone wrong.
>>>
>>> I must say that I have never used the method of updating from CD. I tend to
>>> update the system sources with csup(8), and then rebuild the kernel and
>>> applications from source as explained in the Handbook. This hase never failed
>>> me yet.
>>>
>>>   
>>>       
>> 1. Reporting the errors is a little difficult because more often than
>> not, the errors fly by too fast to be fully understandable.
>>     
>
> Error messages that have happened after the kernel has booted are still saved
> inside the kernel message buffer. With the 'dmesg' command you can have a good
> look at them.
>
> Additionally, a snapshot of this message buffer is written to
> /var/run/dmesg.boot after the filesystems are mounted.
>   
I'll note that and try to get to them.
>   
>> 2. I usually and never (since way, way back) do not update from a CD,
>> except to boot up; I do the rest over ftp from the main source at
>> freebsd.org. and I use cvsup-without-gui. :-)
>>     
>
> I got the impression from one of your previous mails that you tried updating
> from CD.
>
>   
You have to start somewhere... ;-)  As I recall it, I was trying to see
what was to be found on the disk and I did not want to change or commit
before getting that information... but, likeOBSD, I think it decided to
do some writing to the disk - and I even got out of there fast by
turning off the computer thinking that would abort things... stopping is
sometimes rather slow. :-[
>>> Insert a USB thumbdrive and mount it. Copy the files to it, unmount. The
>>> GENERIC kernel on the CD should have all the necessary drivers for this to work.
>>> Assuming that you're logged in as root, and that your USB drive is recognized
>>> as /dev/da0s1:
>>>
>>> mkdir /usbdrive
>>> mount_msdosfs -m 644 -M 755 -l -o noatime -o sync /dev/da0s1 /usbdrive
>>> # copy the files you need...
>>> umount /usbdrive
>>>   
>>>       
>> I'll try that; oddly, I was able to use my SanDisk 4gb cruzer before.
>> Chuck it into usb, mount /dev/cd0 to /mnt and go to it. But now, for
>> some strange reason it just wont mount. I'm getting messages that it's
>> not readable - "g_vfs_done input output error" and attempt to query
>> device size failed, medium may have changed. But the stick is fully
>> insertable, readable, removable from XP; as it was on FBSD. Weird.
>>     
>
> You shouldn't be using the /dev/cd0 device. It is a virtual CD and should be
> read-only. 
>   
But that is what is shown when the memory stick is inserted.  And I did
try da0 (if I recall correctly).
Ok, I just did your little mount suggestion above, and glory be, Massah,
it shore did work. :-)
I really don't know how I ever got this far...
>    
>   
>>> I don't understand what you mean by that? What do you mean by "doesn't act the
>>> same"? 
>>>   
>>>       
>> When turning on the computer, hit del and the bios setup comes on almost
>> immediately on the 3ghz machine. On the 2.4 machine it takes much, much
>> longer to start up (the monitor is Hitachi superScan Elite 812 on the
>> 3ghz machine, hitachi CM751 on the 2.4ghz) and when del is pressed the
>> bios goes through the entire scanniing process and then restarts before
>> finally going into the bios... and the versions of the bios and the
>> setup are both identical in nubers but, if I recall correctly, there are
>> some minor differences in some of the more arcane options that I never
>> even look at. And in general it always ran a bit sluggish.
>>     
>
> If the battery keeping the CMOS memory of the 2.4ghz machine has run out, the
> bios won remember its settings and e.g. has to scan for harddisks etc.
>
> And settings like boot sequence, memory timing etc. can have a lot of
> influence on boot time.
>   
Now that's an unexplored corner of the PC... I'll replace it and let's
see... I did have that problem many, many years ago - I don't recall
what exatly it was, but I think the computer had kind of gone "dead" had
to replace the battery and it worked. Can't even remember how I found
the problem or if someone pointed me to it.
>   
>>> I don't want to be rude, but you could have made a mistake somewhere. If
>>> you're futzing around with disks and partitions it is quite easy to screw
>>> something up. Even for people with lots of experience it is sometimes a case
>>> of PEBKAC. :-)
>>>
>>>   
>>>       
>> I understand what you are saying and I don't take it to be rude at
>> all... actually, I don't screw around with the disks and the
>> partitions... I only try to read them to recover any files I may have
>> lost. So far, I have had 100% success on recovering lost data that was
>> important.
>> Up to now, when I had problems with crashes, I just reinstalled
>> everything, the OS, the programs loaded up the files that were recoverd
>> and whoopie... keep on chugging along. I did exactly that on this last
>> great effort - actually, it took a great deal of patience and
>> application to install the 64bit FBSD with flashplugin on the portable
>> and it took extreme patience to wait for all the updates and upgrades
>> and the searching and figuring out just how to configure and set up the
>> i386 on the 2.4ghz machine - and it all worked beautifully; 
>>     
>
> This is _exactly_ why you need good backups. So that you don't have to reinstall
> everything again if something goes wrong. Blindly reinstalling is a windows
> solution.
>   
True enough. If I have a Windows problem - it's crash & trash -
reinstall & have a ball.
> For your systems that are running well, get an external harddisk that is at
> least as big as the one in the machine. On my website I have explained how to
> prepare this disk in somewhat greater detail:
> http://www.xs4all.nl/~rsmith/freebsd/index.html#usb
>
> Then use the dump(8) command to make
> backups of the internal harddisk partitions and write them to the external
> harddisk. Say that you have mounted the external harddisk at /mnt/backups. The
> following command makes a backup of the entire root partition, and compresses
> it to save space:
>
> 	dump -0 -a -C 8 -L -u -f - / |gzip -1 >/mnt/backups/root-20090813.gz
>
> If you have /usr, /var or /home set up as seperate partitions (which is a good
> idea), make dumps of those in the same way. Make new dumps regularly, so you
> don't loose too much data if you have to restore a broken system. You can use
> the restore(8) program to restore individual files or up to the whole nine
> yards from the backup.
>
>   
>> I was really
>> happy that my ordeal was over and now I could get on with it. Not a nice
>> way to wake up in the morning with the box sputtering out ...
>> No, do not "futz around" - I have been doing my updates with portupgrade
>> - compilin the ports is long and terribly boring - that's usually when I
>> can write long e-mails ;-)  and now I'm trying portmaster - but it is
>> giving me a bit of heartburn - it seems to stumble over itself - the
>> updates dont work too well. It seems, that when the updates span several
>> releases, portmaster does not know what it's doing - I caught it
>> upgrading to an older version when it aborted; and the dependencies seem
>> to suffer from the same kind of behavious. 
>>     
>
> If you are switching between major versions of FreeBSD (like from 6.x->7.2),
> the upgrade tools like portmaster and portupgrade don't always work perfectly,
> for technical reasons that I won't go in to. The only foolproof method in that
> case is to delete all ports and reinstall them.
>
> For normal port updates, even between minor versions of FreeBSD it works very
> well, _provided_ that you read /usr/ports/UPDATING and follow any special
> instructions given there pertaining to ports that you use. Ignore those at
> your peril.
>
>   
>> Make deinstall, make reinstall seems to be the best way... and then sit
>> there and watch the screen expecting to suddenly have the compiling be
>> interrruptted by the configuration scree. And that is often a pain... there
>> are so many options that mostly have no direct meaning for me of use, for
>> that matter. For example, ghostscript - do I really need it? I'm only using
>> 1 printer and that is a postscript Xerox Phaser 8200 that has no driver in
>> the ghostscript files.
>>     
>
> Being a postscript printer it doesn't need a ghostscript driver... But
> ghostscript is required by CUPS (the cups-base port, to be precise). Among
> other things to convert PDF to postscript. Note that you can configure
> cups-base not to use ghostscript.
>
>   
>> And the same for gutenberg... and other
>> dependencies - I suppose that some are needed for various
>> implementations of different programs that call them... but that should
>> really be default settings. And who uses the the new ipv6 stuff?
>>     
>
> Nobody is forcing you to change them. You can use portmaster's -G option to
> prevent 'make config' from running.
>   
But I use the config as there are some tweaks that are needed.