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Thread: Very long mount times of large ext4 filesystems - 12.04.1 LTS

  1. #1
    Join Date
    Aug 2011
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    53
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    Ubuntu 12.04 Precise Pangolin

    Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Hi,

    I'm having problems with the mount times of larger filesystems (I use ext4).

    Info:
    Code:
    root@NAS:~# time mount /dev/vdc /mnt/tempik
    
    real	0m49.696s
    user	0m0.000s
    sys	0m49.339s
    root@NAS:~# time mount /dev/vdb1 /mnt/nowy
    
    real	1m26.682s
    user	0m0.004s
    sys	1m25.949s
    root@NAS:~# uname -a
    Linux NAS 3.2.0-31-generic #50-Ubuntu SMP Fri Sep 7 16:16:45 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
    Both those devs have ~10TBs. The first one is "normal" 32bit fs, and the second one is a 64bit fs (I'm using standard v1.42 e2fsprogs). Smaller drives (eg. 2TB) are mounted without problems in a reasonable time (0-2secs). On oneiric those big devs are mounted in under a second (2-3 seconds max if the hardware is busy). I need at least one of those devs to be mounted during boot (they're not boot drives, nor root fs - they just contain lots of data that some of my startup apps need), but with those mount times I'm getting timeouts during boot. All filesystems are clean.

    Does anyone have an idea what's wrong with precise that it acts this way? And, maybe, how to fix this?

  2. #2
    Join Date
    Aug 2011
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    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Hello again,

    I've resized one of the fs to 16TB, and now the mount times are even more abstract:

    Code:
    root@NAS:~# time mount /dev/vdb1 /mnt/nowy
    
    real	4m19.015s
    user	0m0.000s
    sys	4m17.964s
    I can even live with the OSs boot time of >4min, but how to configure it to wait for that fs to mount properly instead of giving a timeout error during boot, and giving up the mount process. Is there a way to set that timeout ? (in grub, or maybe fstab?)

  3. #3
    Join Date
    Aug 2011
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    Ubuntu 12.04 Precise Pangolin

    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Ok. Now I know that the kernel update is the problem here. After installing a clean 12.04.1 the mount times are ok. After doing an apt-get update && apt-get upgrade && apt-get dist-upgrade the kernel gets updated to 3.2.0-30-generic and the mount times go up (from less then a second to over 4min). Anyone knows how to fix that ??

  4. #4
    Join Date
    Aug 2011
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    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    I've reverted to kernel 3.2.0-29-generic, and everything is fine now. I'll wait with kernel updates until it'll be fixed.
    If this is some new bug, can someone tell me how to get it to the Ubuntu support, so they know about it ?

  5. #5
    Join Date
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    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    If you ask for help, do not abandon your request. Please have the courtesy to check for responses and thank the people who helped you.

    Blog · Linode System Administration Guides · Android Apps for Ubuntu Users

  6. #6
    Join Date
    Apr 2008
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    2

    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    I can confirm this bug on an up-to-date 12.04 install (Kernel 3.2.0-30). Mount time for a 10TB device is over one minute.

  7. #7
    Join Date
    Apr 2006
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    996
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    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Quote Originally Posted by SeijiSensei View Post
    ...
    Xye incredibly difficult puzzle game with minimal graphics. Also at playdeb
    Got a blog: Will Stay Free

  8. #8
    Join Date
    Oct 2008
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    Angry Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Quote Originally Posted by szafran View Post
    Hello again,

    I've resized one of the fs to 16TB, and now the mount times are even more abstract:

    Code:
    root@NAS:~# time mount /dev/vdb1 /mnt/nowy
    
    real	4m19.015s
    user	0m0.000s
    sys	4m17.964s
    I can even live with the OSs boot time of >4min, but how to configure it to wait for that fs to mount properly instead of giving a timeout error during boot, and giving up the mount process. Is there a way to set that timeout ? (in grub, or maybe fstab?)
    Can confirm similar behavior. See my comments at https://bugs.launchpad.net/ubuntu/+s...x/+bug/1054605 ...

    Code:
    root@AGVault:~# time umount /data
    
    real 0m1.031s
    user 0m0.000s
    sys 0m0.028s
    root@AGVault:~# time mount /data
    
    real 3m55.614s
    user 0m0.000s
    sys 3m37.050s
    Actually, szafran, if it's you who posted the bug report, you should do also some extra stuff. Se comment #2 https://bugs.launchpad.net/ubuntu/+s...605/comments/2

  9. #9
    Join Date
    Aug 2011
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    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    Actually, I didn't officially report any bugs on Ubuntu. Don't even have a Launchpad account (that's the main reason, that I don't report bugs on Ubuntu - I don't want and don't need that account).

    As for now I can only confirm what has been said before.

    All of above filesystems were created using:
    Code:
    mkfs -t ext4 -T big -m 0 -v -b 4096 -L <label> <dev>
    df -h on the filesystems:
    Code:
    /dev/sdf2       459G  198M  459G   1% /mnt/tempik
    /dev/md5p1       11T   10T  865G  93% /mnt/mag1
    /dev/md5p2       11T  159M   11T   1% /mnt/mag2

    Mount times on 3.2.0-31-generic kernel (same goes for 3.2.0-30-generic):
    Code:
    root@NAS:/mnt# time mount -O noatime /dev/disk/by-label/tempik tempik
    real    0m0.299s
    user    0m0.004s
    sys     0m0.168s
    
    root@NAS:/mnt# time mount -O noatime /dev/disk/by-label/mag1 mag1
    real    1m10.703s
    user    0m0.004s
    sys     1m7.964s
    
    root@NAS:/mnt# time mount -O noatime /dev/disk/by-label/mag2 mag2
    real    1m11.026s
    user    0m0.000s
    sys     1m8.052s
    And to that there's that jbd2 process running every second or so. Don't really know what it does, but it reads/writes a lot. And therefore overall speeds on those drives go down.

    And now for 3.2.0-29-generic kernel:
    Code:
    root@NAS:/mnt# time mount /dev/disk/by-label/tempik tempik
    real    0m0.088s
    user    0m0.000s
    sys     0m0.048s
    
    root@NAS:/mnt# time mount /dev/disk/by-label/mag1 mag1
    real    0m0.318s
    user    0m0.000s
    sys     0m0.068s
    
    root@NAS:/mnt# time mount /dev/disk/by-label/mag2 mag2
    real    0m0.762s
    user    0m0.000s
    sys     0m0.384s
    The jbd2 process is still messing with the drives. So it's not good on this kernel too.
    The jbd2 process is messing with small and big filesystems.

    Conclusion:
    I don't advise to anyone using bigger filesystems to upgrade the kernel over 3.2.0-29-generic - just don't do it 'till it's fixed

  10. #10
    Join Date
    Apr 2006
    Beans
    996
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Very long mount times of large ext4 filesystems - 12.04.1 LTS

    You actually do need an account in some bug tracker if you'd like this bug to be fixed. Developers don't usually read these forums.

    If you don't like launchpad for some reason, then try posting about it in the kernel's bug tracker or is it a mailing list? I doubt this is something that happens only in the distribution anyway.
    Xye incredibly difficult puzzle game with minimal graphics. Also at playdeb
    Got a blog: Will Stay Free

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