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**dibl** · Nov 09, 2008, 08:17 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Nice writeup -- thanks Qqmike!

Although I have "Case #2" I guess I must have "accidentally" avoided a problem due to (a) installing new Grub on the MBR of a different hard drive, and (b) reformatting my filesystem partition when I installed 8.10. I let it overwrite the MBR which is on the IDE drive, and it did pick up my second OS, and wrote a correct boot menu.*

*Of course, as always, the Linux installer ID's my first SATA drive as hd(0), whereas Grub sees the IDE drive (where the MBR with boot instructions is located) as hd(0) and therefore tries to boot from it, resulting in Error 15. A manual edit to the boot menu to change hd(0,0) to hd(1,0) for Kubuntu, and hd(3,0) to hd(4,0) for sidux fixes it.

**Qqmike** · Nov 09, 2008, 08:28 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Good point you make dibl:

If you install 8.10, and if you let it write its GRUB to the MBR of your current BIOS-first-boot drive, than you will be OK. Intrepid's GRUB will boot HH and prior; however, HH's GRUB (and prior) may not boot 8.10.

Thanks, dibl, for pointing that out.

ps dibl, ah! ... your drive enumeration with mixed IDEs & SATA .. I remember all that you went though; as you know, nice thing about GRUB is that by hook or by crook, you can get in there manually and make it whatever you wish! just a pita now and then ... BUT it is good practice for us old folks who need to keep the brain sharp

**dibl** · Nov 09, 2008, 08:57 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

I think it is a "feature" of the Intel chipset on my motherboard that there's some kind of logic that goes "If a hard drive is connected to the IDE bus then that guy trumps whatever may be connected to the SATA bus, for MBR-seeking purposes, regardless of what dibl may have set the boot sequence to say".

**Qqmike** · Nov 09, 2008, 09:08 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

About the GRUB Error 2 ...

tip:

If you had your 8.10 installer put GRUB in the same partition you put 8.10 into (i.e., not into any MBR), then if you are dropped to Error 2 AFTER getting the grub boot menu, then you can probably (as I did) get into your new 8.10 OS by chainloading:

Press "c" to get a grub> (GRUB prompt)
grub> chainloader (hdx,y)+1
grub> boot
where (hdx,y) is the partition that the new 8.10 is in.

**tinker** · Nov 10, 2008, 07:27 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Grub can use blkid as well as device node. Something like that might help with your issue dibl. But I may have misunderstood, I read through this quickly.

**tinker** · Nov 11, 2008, 03:32 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Originally posted by tinker

Grub can use blkid as well as device node.

I don't see why no one called me on this, it is completely wrong. I know both of you guys are expert enough to know it is wrong. Anyway, this post is to set the record straight for anyone else reading it.

Sorry for the noise guys. This is not a valid excuse, perhaps it is a reason. Yesterday I was working as fast as I could, trying to read through the new posts since I was last online when I noticed that I had to leave quickly and soon to make a ferry to go to the hospital. The test I had to do required me to be fasting since the previous day so I think my mind disconnected from my body. I posted anyway. Let that be a lesson to me, I shouldn't write when I don't have time to think through what I am writing or if I am not sure about it.

**Qqmike** · Nov 11, 2008, 07:16 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

tinker: "I don't see why no one called me on this, it is completely wrong."

I plead ignorance ... I wasn't sure what you meant by the statement, but after seeing UUID in 8.10 GRUB menu.lst (instead of root (hdx,y), I figured it's a new world anyway ...

**tinker** · Nov 12, 2008, 03:50 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Originally posted by Qqmike

I figured it's a new world anyway ...

Yes, and the change seems to be accelerating. I often feel like I am being left behind with this dialup account. It's hard to get enough information down a small pipe. I don't yet have 8.10 nor have I had any time to play with GRUB2 or this or that or some other thing that someone will ask about.

**Qqmike** · Nov 12, 2008, 06:35 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

tinker, yes on all accounts.
>> I didn't have dial-up until early 2006. Once you get it, you'll wonder how you got along without it. Even the standard 1.5Mb/s DSL is sufficient (which is all I have to this day--Earthlink).
>> 8.10--just installed it into an "experimental" partition and must find time to learn the new non-Desktop paradigm.
>> GRUB2--same here. Do you have a readable source on it? I have not looked into it lately. Last time, 6 mo ago, I could only find the cryptic stuff. Tried it once, and it trashed my whole setup (or, I should say that I trashed my whole setup).
--Mike

**tinker** · Nov 13, 2008, 06:25 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

[quote=Qqmike]
>> I didn't have dial-up until early 2006. Once you get it, you'll wonder how you got along without it. Even the standard 1.5Mb/s DSL is sufficient (which is all I have to this day--Earth]
Unfortunately, I live on an island a long cable run from the telco central office and, to complicate matters further, there is a concentrator along the run. Telco would have to replace that concentrator with a remote switch in order to serve ADSL. There is no cable TV here so the only option is satellite Internet and I don't want to spend that kind of money.

I can only sustain connections of roughly 3.0 to 3.8 KBytes, the concentrator affects the bandwidth as well as the long run of copper. It's a USR courier too, a very good modem. I have tested this over and over at all times of day with files of different sizes and to many worldwide sites. Its the user experience that I'm stuck with for now, not enough of us out here for either company to make the investment in equipment at this time.

I do, however, leech off of friends broadband when I visit and bring stuff home on my laptop. But I can't just go visit for that specific reason.

Originally posted by Qqmike

>> 8.10--just installed it into an "experimental" partition and must find time to learn the new non-Desktop paradigm.

Yup, on my 'list' too.

Originally posted by Qqmike

>> GRUB2--same here. Do you have a readable source on it? I have not looked into it lately. Last time, 6 mo ago, I could only find the cryptic stuff. Tried it once, and it trashed my whole setup (or, I should say that I trashed my whole setup).

No, so far I'm struggling with that "cryptic" stuff too. I'll let you know if I find anything definitive.

**Qqmike** · Nov 13, 2008, 06:28 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Thanks for your reply tinker

**tinker** · Nov 22, 2008, 08:23 AM

UUID mounting in menu.lst -was Re: GRUB Error 2 ...

@Qqmike

I finally had the time to check this out further and I did promise to share information but sorry about the time lag being fairly long.

The system I tested on has a CMD IDE controller with two IDE channels in addition to the two IDE channels already available. I have 4 IDE devices in total so, because of the extra controller, each device is attached by its own ribbon cable. I don't think that configuration matters and it was done that way because there aren't 8 drives, so each can have a ribbon cable to itself, I just mentioned it for completeness and as the cmd conroller module might be related to the situation described (different ordering).

What seems to happen is that, since some point below at the 2.6.18 kernel, they are not always assigned device nodes in the same order when the IDE drives are enumerated, I didn't observe this behaviour in earlier kernels. It probably has something to do with the loading of the CMD controller module but that's as far as I can guess. At boot time there are two different orderings of the physical IDE drives for hda; hdc; hde; hdg and it is somewhat random which way they will come up on each boot. If we think of the physical drives as 1; 2; 3; 4, sometimes they come up, hda as 1; hdc as 2; hde as 3; hdg as 4 and sometimes it's hda as 3; hdc as 4; hde as 1 and hdg as 2. Sometimes it comes up the same way for several times in a row and sometimes it changes on one reboot, I have not been able to find a pattern for this behaviour in many (more than 100) reboots. This situation often took several reboots to get a system specified by device node to work.

So, here is the part that might apply to our discussion here.

I modified the stanza for each distro in the menu.lst to use the UUID of its partition rather than device node for the root= portion of the kernel line.

Code:

Example:
#kernel		/boot/vmlinuz-2.6.18-6-686 root=/dev/hdg3 ro vga=789
kernel		/boot/vmlinuz-2.6.18-6-686 root=UUID=190011e9-df68-4b9b-b1a7-fab3a8afabf6 ro vga=789

I have partitions in my static filesystem table specified in two different ways, some are mounted by LABEL= and some are mounted by UUID=. Both methods work successfully and acceptably. Since none are mounted by device node, physical device ordering doesn't matter and it boots the system successfully with whichever ordering happens at boot time.

This gets around the two different orderings that are assigned to the drives and the resultant device node mounting confusion on this system. It might also be tried as a solution for the situation dibl mentions in reply #1, in order to get around that manual edit. I only had IDE drives on this system so that's all I could test.

**Qqmike** · Nov 22, 2008, 08:34 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

tinker -- Hi.
Interesting. Good experiments. I have also experimented with UUIds with respect to flash drives and external HDDs and the UUIDs do seem to do what they're supposed to do--to be unique identifiers that can't be fooled by connecting and un-connecting and reconnecting.

Device enumeration, related ...
I pasted this from my notes, a stream of postings on it, with dibl quoting a dev guy about is, and with some links; here it is, "as is":

dibl's post at Kubuntu, 6-21-08:

The enumeration of drive-like devices was pretty simple and obvious as long as there were only hard disk drives -- even the emergence of the SCSI bus and SCSI drives didn't cause a lot of problems. But, with the advent of the USB bus, and all the kinds of devices that can be plugged into it, including hard drives, memory sticks, Compact Flash, and SD cards, the *nix developers have had their hands full trying to keep up. I also follow the development of sidux, and the poster "slh" on this forum is actually a kernel developer and so I take his observations more seriously than most:

http://sidux.com/index.p....=#85668

On my desktop system, I have one IDE drive and 4 SATA drives connected, and there is simply no reliable way to predict how any given Linux installer is going to number my drives -- setting up the /boot/grub/menu.lst is always an exercise in experimenting with (hdn) where "n" is the mystery location where Grub went.

See: http://kubuntuforums.net/forums/inde...pic=3095584.15

- - - - - - - - - -
- - - - - - - - - -

slh post, June 20, 2008:

Device enumeration is not stable in any distribution released within the last 18 months (it wasn't even guaranteed to be stable in the past, even though it was quite likely to appear "stable"), the UUIDs are pretty much guaranteed to remain stable, that's why they are used in every distro these days.

This gets even more obvious on libata using distros, where "everything" uses the /dev/sdX namespace (PATA, SATA, SCSI, USB, firewire, CF cards, basically everything); devices are enumerated in the order they get detected while booting, which is (semi-) random.

See:
http://sidux.com/index.p....=#85668

Edited by mikemqa on Jun. 21 2008,13:07
{End of the pasted quote]

**tinker** · Nov 23, 2008, 05:57 AM

Re: GRUB Error 2 -- 8.10 Multiboot w 8.04 or prior

Yes Qqmike, all good information for anyone lurking and following this thread in the interest of learning.

BTW, I know slh (the Sidux dev mentioned) really knows his stuff with regard to the kernel. Slh did the kernel stuff for Kanotix before Sidux was born and I have used both of those distros.

I certainly understand the reason why UUIDs have value over device node mounting and the test system I used for my test has 16 separate partitions so getting them in the correct order is fairly important. However, as I have stated previously in a different post, for a simple workstation install I prefer mounting by label. My preference is to not have many things automounted and it's easier for me to remember a label like, "storage", "mirror" or "backup" than a UUID string. That way, at runtime, I can just issue the command, mount -L storage, for example. Note: GRUB will do LABLE= mounting too.

There are times when I feel that the fact that GNU/Linux has so many options is a curse as well as a blessing. It sparks a lot of newbie confusion and questions, especially from people who expect only one right answer to a question.

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