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Thread: Ubuntu installation fail detect 1TB HDD's partitions

  1. #1
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    Ubuntu installation fail detect 1TB HDD's partitions

    Hallo everyone!

    If this question has been aswered in another thread, please forgive me and please direct me to the thread.

    To get to my situation scenario, I currently have this hard drive setup in my machine:


    I want to dual boot Windows 7 and Ubuntu 11.04 x64. The 38GB partition on the 250GB hard drive is intended for Ubuntu and the rest for personal space and Windows 7 operating system.

    While installing Ubuntu from the CD, it prompted me that no other operating system has been detected. I stopped the installation at this point (as I did not want GRUB to take over my current Windows MBR) and booted the live CD, just to notice that Ubuntu cannot detect my whole Western Digital 1TB drive. Could this be due to anything I have done with the partitions?

    Kind regards,
    N

  2. #2
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    Ubuntu 10.10 Maverick Meerkat

    Re: Ubuntu installation fail detect 1TB HDD's partitions

    Hi and welcome. There are some possibilities. Has that 1TB drive ever been used in a RAID array? The Ubuntu installer will not even see a drive that has Windows RAID signatures on it, although it ought to.
    Try booting the live CD and "trying without installing"
    Open a terminal and run
    sudo sfdisk -luS
    You should find that this lists all your drives and partitions and gives them names of the form sdxy. Windows drive names like C: and D: are meaningless to linux. Please post the output.
    Then run
    sudo dmraid -r
    and this will list any Windows RAID devices detected.
    To erase the RAID signature (or super-block) on drive /dev/sdx (x=drive letter for 1TB drive)
    sudo dmraid -E -r /dev/sdx


    ASRock P67 Extreme6, Intel i5 2500K, 8GB RAM, nVidia 6600GT, 4x1TB RAID1+0

  3. #3
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    YesWeCan's suggestions are proper; however, instead of (or in addition to) "sfdisk -luS", I recommend:

    Code:
    sudo fdisk -lu
    This has the advantage of providing the disk size in a more precise form, which can be important in properly diagnosing at least one possible cause of the symptoms you describe.

    My FixParts program can correct many of the partition table irregularities that can cause these symptoms. It won't do any good for RAID-related causes, though.
    If I've suggested a solution to a problem and you're not the original poster, do not try my solution! Problems can seem similar but be different, and a good solution to one problem can make another worse. Post a new thread with your problem details.

  4. #4
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    Thank you for the replies gents!

    Please find the pasted pictures of the various commands below this post. With the information I have given you, should I attempt sudo dmraid -E -r /dev/sdx ? Also, what will the command do to my partition on the hard drive? I hope I do not lose any data. Although backing up is an option at the moment.

    sfdisk picture:


    dmraid picture:


    fdisk picture:


    Kind regards,
    N

  5. #5
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    Sorry for the unusual large pictures added. I did not think twice before adding the pictures this morning before I went to the office.

    I think it is perhaps important to add that the 1TB drive I am using, is newly purchased (like 2 weeks ago) and only partitioned using the Windows 7 installation DVD. Could AHCI perhaps make the partitions look like some form of raid?

    Kind regards,
    N

  6. #6
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    The dmraid -r shows that sda has raid signatures on it. That's your problem.

    sudo dmraid -E -r /dev/sda

    to erase them
    ASRock P67 Extreme6, Intel i5 2500K, 8GB RAM, nVidia 6600GT, 4x1TB RAID1+0

  7. #7
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    Quote Originally Posted by srs5694 View Post
    This has the advantage of providing the disk size in a more precise form, which can be important in properly diagnosing at least one possible cause of the symptoms you describe.
    Please elaborate.
    ASRock P67 Extreme6, Intel i5 2500K, 8GB RAM, nVidia 6600GT, 4x1TB RAID1+0

  8. #8
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    (re: "fdisk -lu" being superior to "sfdisk -luS" for diagnosing some problems that can produce the OP's symptoms.)

    Quote Originally Posted by YesWeCan View Post
    Quote Originally Posted by srs5694
    This has the advantage of providing the disk size in a more precise form, which can be important in properly diagnosing at least one possible cause of the symptoms you describe.
    Please elaborate.
    Consider Roobir's output for /dev/sda. This indicates that the /dev/sda3 partition ends on sector 1,953,521,663. Both "fdisk -lu" and "sfdisk -luS" provide this information. By itself, though, this information doesn't tell you if that partition is sized properly for the disk. For that, we need the disk size. The sfdisk output provides this via a cylinder/head/sector triplet -- 121601/255/63 in this example. Multiplying those three numbers, you get a disk size of 1,953,520,065 -- that is, smaller than the /dev/sda3 partition! If you'd done this check and didn't realize its limitations, alarm bells would be ringing and you might go to a lot of needless effort to correct this "problem."

    Unfortunately, the CHS values provided by sfdisk are only ROUGHLY correct. The issue is that modern disks seldom have an integral number of cylinders; they're laid out using a more complex geometry than the antiquated CHS values permit, so there are usually sectors available for use after the final whole cylinder. You can learn the precise size of the disk -- and without having to do multiplication manually -- by using fdisk instead of sfdisk. Roobir's fdisk output reveals the true size of the disk to be 1,953,528,168 sectors -- significantly larger than the end point of the final partition. Thus, there is no problem with that partition's size.

    Of course, if you're aware of this limitation, you could try adding 1 to the number of cylinders, and you'd find that the end point for /dev/sda3 would be less than this value -- but then, so is the true number of sectors on the disk. This test could therefore lead to a false sense that everything's OK.

    Furthermore, the presence of the total disk size in the fdisk output facilitates this important comparison -- you can easily find the final partition and compare its end point to the disk size. With sfdisk, you've got to do the math first, which adds to the effort and increases the risk of human error causing a misdiagnosis.

    All of this is important because there are tools that are known to produce partitions that are too big for the disk. TestDisk sometimes (but not always) does this with the extended partition it creates to encompass logical partitions. When parted encounters such disks, it reports them as being empty. Thus, to diagnose this problem, precise information on disk size is required, and "sfdisk -luS" just doesn't provide that information. Both commands do provide other useful diagnostic information -- they can both help you spot overlapping partitions, for instance. sfdisk shows empty partitions, which could conceivably be useful if stray data in such a partition table entry was causing problems -- but I have yet to hear of such a problem in the real world. Thus, "fdisk -lu" provides better diagnostic information for this problem than does "sfdisk -luS".
    If I've suggested a solution to a problem and you're not the original poster, do not try my solution! Problems can seem similar but be different, and a good solution to one problem can make another worse. Post a new thread with your problem details.

  9. #9
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    In summary, fdisk -lu shows the total number of disk sectors and sfdisk -luS does not.

    I knew that.

    I would still use sfdisk -luS for these symptoms.
    ASRock P67 Extreme6, Intel i5 2500K, 8GB RAM, nVidia 6600GT, 4x1TB RAID1+0

  10. #10
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    Re: Ubuntu installation fail detect 1TB HDD's partitions

    Quote Originally Posted by YesWeCan View Post
    The dmraid -r shows that sda has raid signatures on it. That's your problem.

    sudo dmraid -E -r /dev/sda

    to erase them
    Will I lose any of the data on that drive by using the command?

    Thank you both for the responses!

    Kind regards,
    N

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