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  1. #1

    Slow boot after RAID setup

    I've just finished setting up a RAID 1 on my system. Everything seems to be okay, but I have a very slow boot time. It takes about three minutes between the time I select Ubuntu from GRUB and the time I get to the login screen.

    I found this really neat program called bootchart which graphically displays your boot process.

    This is my first boot (after installing bootchart).

    h ttp://

    I'm not an expert at reading these, but it appears there are two things holding up the boot, cdrom_id and md_0_resync. I tried unplugging my CD drive SATA cable, and this is the new boot image.

    h ttp://

    It's faster, but it still takes about a minute, which seems pretty slow on this system. The md0 RAID device is my main filesystem. Is it true that it needs to get resynced on each boot?

    I'm not sure how to diagnose my CD drive issue. The model is a NEC ND-3550A DVD RW drive. I should also note that there's a quick error message at startup about the CD rom. It's too quick for me to read it, just one line on a black screen saying "error: cdrom something something".

    I'm not sure what other information to include. Thanks for any help.

  2. #2
    If the md raid is resync'ing it's because it wasn't powered down properly or you never let it get sync'ed in the first place.

    You can see the progress of the sync via /proc/mdstat:

    cat /proc/mdstat
    Just like any RAID set, it must replicate from primary > secondary drives. Afterwards, it will be in sync, unless something (like a hard power-off) causes it to require a resync.

  3. #3
    Ah fantastic. Thank you. It's taking quite a while to resync. I didn't think it would take so long. The current ETA is over 12 hours from now. I don't suppose you know a way to speed it up?

    Also, do you have any ideas on diagnosing my DVD drive problem?

    Thanks for your help. I really appreciate it.

  4. $spacer_open
  5. #4
    The resync speed can be set to a maximum, but I don't believe any current distro's do this. You didn't list the current speed, so no one knows what you're seeing. Doing the math, a 1TB array will take a while even at 100MB/sec.

    The resync is also only as fast as the slowest drive - if one is older/having a problem, the resync will be at its speed.

    No, I don't have any suggestion about your DVD drive. You can review the output of dmesg and check the messages log while the OS is running to determine if it's having ongoing problems.

  6. #5
    I just set up a 2 TB RAID 1 array a few days ago using mdadm.
    The first time I set it up, the web page I was using for instructions
    forgot to mention 2 major steps.
    First you need to add an ARRAY config line to the mdadm config file.
    The second issue was they forgot to mention that you can't reboot the pc until
    the array is fully sync'ed.

    I ended ripping it apart and redoing it according to another set of instructions I found.
    The array is now working fine.
    The initial time to sync the drives was about 6 hours.
    Current read speeds are 110 Mb/sec

    Boot times are about 10 seconds longer then before I installed the array.
    Which is still well under a minute on 10.04

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