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Thread: Grub Error 21

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  1. #31

    Hey Saikee.. thanks for the tip. Downloading puppy right now. Cheers.

  2. #32

    Make no mistake about this. I could be wrong.

    Casper is the real expert giving very good advice all the way. It is a bad practice for a third party to add other suggestions as they can confuse you and distract you from the main advice given by Casper. I did so because I thought my contribution "may" expedite the solution and have been carefully to be suggestive and complimentary to the main advice already given out.

    If I am proved wrong then at least I can correct my misconception learn something from Casper.

  3. #33
    SuperMod (Back again) devils casper's Avatar
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    hi !

    something worked atlast !

    i agree with saikee again. create /boot partition in Internal Disk. in cases where BIOS doesn't support boot up from External Disk, we left with only a few workarounds.
    * create /boot partition in Internal Disk and install GRUB in MBR of Internal Disk.
    * create all partitions in External disk including /boot, install GRUB in the boot sector of /boot or / partition and use Windows Boot Loader. edit boot.ini using Bootpart.
    * use third party Boot Loader like Smart Boot Manager.

    i have never tried Puppy and dont know how its GRUB works.

    saikee, i am still learning. i have practical knowledge only, never read manuals/books and i am sure you have read a lot of manuals, books and you have in-depth knowledge of GRUB and boot procedure. i read a lot of your other posts and learned stuff from those.

    hope to see you around and learn more from you !!

    saikee, you have edited post # 22 and i missed that.
    here is my reply to that EDITED post.
    Quote Originally Posted by saikee
    If you don't attack others contributing information to the thread then there would be no need for you to waste any time.
    am i attacking? who has started all this? try to be polite while posting else you will get similar replies from my side.
    Quote Originally Posted by saikee
    This post is about booting a Linux from an external USB hard disk.
    I offered my experience by saying it is not possible with Grub. I even offered the way to prove it with Grub's geometry command.
    This was rejected by you without any technical basis.
    i have never tried 'geometry' command and i didn't comment on that post of yours. did i?
    regarding possibility of Booting up from External Disk through GRUB, its possible. if you are saying that it is not possible according to Your Experience, then you are missing a lot of things and its time for you to search around, try a few more things and get some more experience.

    i have never suggested OP to accept/reject your suggestions.

    Last edited by devils casper; 02-05-2007 at 05:56 PM. Reason: added reply to saikee's edited post #22.
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  5. #34

    If you don't mind I would like to terminate all discussions unrelated to the thread.

    I have a confession to make here as I have found a PC that may accept Grub booting from external disk, even I have not tried it.

    I have 3 PCs. The main one has 150+ system inside and a very old one that I use mainly for BSD and Solaris systems. The old PC was left by my son after he finished university. The middle one is mainly for downloading.

    I has been a while since I last used distros from an external disk so I refresh my memory by installing Puppy as I have used it successfully before but could remember on which computer.

    To my amazement the installation doesn't boot from my main box which is the newest and it distinguishes external disks as a USB devices.

    I then tried the oldest PC which "does not" distinguish external disks from internal disks. They are just named hdd0, hdd1, hdd2 etc. In that PC when I interrogate from a Grub floppy, which on boot up has Grub and no Linux, it was the first time I saw the external hard disk being reported.

    I am using the just-installed Puppy booted from an external USB hard disk on this old PC to do the reply.

    My current conclusion is some Bios can recognise the external disks but others may not. Therefore my assertion of Grub doesn't boot from an external hard disk may not be entirely correct as some PC may be able to do it. This may explained some users never reported a difficulty of booting from an external hard disk while others simply could not get through no matter what.

    I shall explore further and report back.

    I have not paid much attention to the external hard disk booting in the past because it is a hit and miss type of adventure. I did have a couple of distros installed but never gone deep into it because I could not use Grub.

  6. #35
    I will leave you guys to think for what it is worth but here is the result of my investigation with 3 PCs.

    PC1 : Asrock 939 NF4G-Sata2 with AMD64 3200 (newest)
    PC2 : MSI K8T Neo with Athlon 64 3000
    PC3 : Asus A7N8X-E with 32 bit Athlon 2800 (oldest)

    All 3 PCs have been set to boot the USB hard disk first.

    When the USB hard disk is connected and the machine is booted to a Grub floppy first Grub can't see the USB disk in PC1, reports disk read error in PC2 but can recognise the USB disk in PC3.

    Thus I managed to install

    (1) Puppy 1.0.6 in sda1 a fat16 partition as its boot loader syslinux requires it. It boots satisfactorily.
    (2) Slax 5.1.8 in sda6 in standard Ext3 partition and so is the rest.
    (3) Mandriva Free 2007 in sda7
    (4) Sidux 2007 (formerly Kanotix) in sda8

    I verified each system boots individually by a Grub menu hosted by Mandriva. I tried to install Sabayon and Ubuntu in sda8 and sda9 too but the installation weren't successfully, something the installers complained.

    That external disk was working alright until I offered it to either PC1 or PC2. Both PCs can't recognise the disk or no booting system detected.

    There seems to be a stability issue too as the disk became unbootable in PC3 too in two occasions. It is a brand new Samsung 400Gb Pata with about 10 partitions created at the front end and now I am having problem for it to be recognised as an ordinary USB disk (not for booting). The disk may have hardware problem but I did played around with the 4 distros for the whole evening.

    Thus my conclusion is the ability to boot Linux depends on the motherboard. I cannot be absolutely certain but I believe I had the PC1 and PC2 booted up Syslinux-based distros in USB pen drives before . I never check the behaviour with USB external hard disks. USB pen drives are of course smaller and usually formatted to Fat16. I only see Fat32 in 4Gb pen drives recently. USB hard disks on the other hand can be several hundred Gb large and so can use the standard Linux Ext3 filing system.

  7. #36
    SuperMod (Back again) devils casper's Avatar
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    if BIOS supports booting up from External Disk and its not booting even after installing Linux correctly, then problem is in GRUB configuration files.

    when you start installation, machine boots up from CD Drive. installer assigns device names to harddisks according to BIOS configuration. in some machines, (hd0) to Internal Disk and (hd1) to External disk. now here is the problem. it configures menu.lst/grub.conf and files accordingly. after installation, when you select Boot up From External Disk, External disk becomes (hd0) and internal becomes (hd1). GRUB throws errors.

    solution... edit and menu.lst files.

    if BIOS support booting up from External Disk, its Possible to Boot *any* distro from External disk. BIOS creates problems sometimes ( wrong device name assignment ) but its really easy to fix.

    It is amazing what you can accomplish if you do not care who gets the credit.
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  8. #37
    There are three tests possible to see if an external disk recognised.

    (1) set the bios to boot the USB hdd

    (2) See the actual device name appears in the Bios Cmos setting (only possible with some motherboard like PC1 and PC2 but for possible with PC3 as it just name it USB-HDD generically)

    (3) Boot up a Grub floppy and type
    geometry (hd0)
    geometry (hd1)
    etc until the last disk is exhausted. The geometry (hd0) is equivalent to Linux's fdisk -l /dev/sda except it is in Grub.

    My problem is the mobo PC3 could recognised before it but can't now. I check the USB disk is good and can be detected by booted up systems in other PC.

    My USB hard disk is actually in a caddy and so it can be removed from the external enclosure and inserted as an internal disk. In such a case all the partitions would show up.

  9. #38
    SuperMod (Back again) devils casper's Avatar
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    which harddisk do you have, SATA or PATA?

    It is amazing what you can accomplish if you do not care who gets the credit.
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  10. #39
    PC1 has 3 Pata and 2 Sata.

    PC2 has two empty Pata bays and one filled Sata normally

    PC3 has 3 Pata bays with onlt two occupied. I have removed all internal disks so that it can only boot to the external USB disk.

    If I don't need the disk for booting I can use any disk on any PC bacuse all my hard disks are jumpered to cable select. The Pata and Sata caddies are different and so are their connectors.They cannot be mixed.

    For obvious reason to make it easier I have removed all internal disks in PC1, PC2 and PC3 when booting to an external USB disk. The external hard disks are Pata only and I have 3 external enclosures to choose from. External enclosures for Sata are uncommon and has been probably killed off by the new e-Sata standard allowing a Sata to be hotplugged directly the mobo.

    It is long overdue that I should take a serious look at booting from the external disks. I was hoping by delaying it so that by the time I try all the teething problems have been ironed out and the blood on the brick wall isn't mine. May be it is time for me to bottom it out. The equipment I have does allow me to carry out investigation quickly. It is the time that I am short of.

  11. #40
    SuperMod (Back again) devils casper's Avatar
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    Sometimes, its a bit problematic to make External Disks boot.
    check these two threads. one is using PATA and other has SATA disk.
    thread1, thread2.

    It is amazing what you can accomplish if you do not care who gets the credit.
    New Users: Read This First

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