ext2 on large disk

  • dknightd

    dknightd - 2004-06-13

    I'm trying to exhange files with a linux (redhat 7.2) user.
    The idea is to ship a 500GB LaCie d2 "big disk" back and forth.

    I sent him the disk formatted Macosx UFS. Unfortunately he aparently can't read the disk (Redhat 7.2). I think we can
    work around this (I hope). What i sent is only 30GB and we think he'll be able to move the files around somehow at his end. But then he has to send me back around 250gb of data (lots of 25Mb or less files if that makes any difference).

    My qustion is, if I install extfsx on my mac (imac 17" flat screen, os 10.34) is there a pretty good chance I'll be able to read
    chance that I will be able to read
    the disk if he formats on his linux machine as an ext2/3?

    • Brian Bergstrand

      Well, I would generally say there would be no problems, but there is a recent thread on this list that claims there are issues with large drives ("kernel panic with iomega hdd 250 ext3"). From his description though it may actually be a problem with any drive that is 60% or more full. I have yet to to test this out, but keep it in mind and take a look at that other thread.

      FWIW, I've copied the entire Apple Developer directory w/o problem and that is about 20K files @ 1GB. I've also tested individual files up to 4.5GB w/o problem.


    • dknightd

      dknightd - 2004-06-16

      Well, we are going to give it a try. Looks like he
      has about 300gb of data to put on the disk so it
      will be about 60% full. Hope this works. I'll let you know.

    • dknightd

      dknightd - 2004-06-16

      To test the 60% theory, I created a 256MB ext2 disk image.
      Then filled it up. No problem.
      Of course this was a disk image, not a real disk,
      and a small one at that.

      • Brian Bergstrand

        Well, that's very cool. Thanks for that. Maybe it is just large disks then. Let me know if you have any problems.


    • dknightd

      dknightd - 2004-06-17

      Well my partner in this effort started to write my disk.
      Unfortunately the only way he can connect this disk
      to his linux system is via usb1. At that rate we estimate
      it will take 4-5 days to write the data. (good thing
      he was not using this disk to do the work!)
      This gives me lots of time to decide if I'll need to
      make a linux box to read the disk, and to build
      the box if needed. I also decided I wanted to be
      able to back up the data locally. So I bought another
      500gb disk to experiment with while I'm waiting.

      I formatted the new disk as ext2 using ext2fsx.
      Last night I wrote about 260gb of data to the disk.
      This morning I wrote some more data - no problems.
      Then I used the extFSmanager pref pane to enable
      indexed directories. remounted the disk. Copied
      another 40gb of data to the disk. BTW, it seems
      enabling indexed directories can not be undone
      (at least not by the pref pane). It might be my
      imagination (I didn't time things) but it seems that
      enabling indexed directories slows down writes
      a little bit. Then I enabled ignoring permissions.
      remounted the disk again. and am currently
      writing another 40gb of data to the disk.
      BTW, it is not clear to me the difference between
      unmounting a disk and ejecting it. The extpref pane
      only allows me to unmount it. Disk Utility gives
      me the option to do either. Using the finder controls
      I guess ejects it. It appears they are functionally
      equivalent and result in a clean filesystem.
      So anyway, so far I have written about 325gb of
      data to the disk. read and writes are working fine.
      Unmounting and remounting the disk seems to
      be working fine. I am getting more confident that
      this is going to work. As long as the ext2 file
      system created by his linux box (running one of
      the fudora versions of redhat) is the same as
      the one created by ext2fsx I should be good to go.
      It doesn't appear that ext2fsx has a generic problem
      with large file systems. I don't think I'll bother building
      myself a linux box for home.

      If you have any more tests you'd like me to run
      on this big disk, just let me know. Once my other
      disk is in the mail I'm going to reformat this one
      as an HFS+ volume. Probably next week sometime.

    • dknightd

      dknightd - 2004-06-27

      This is going to be a pretty long posting,  sorry, but,
      I hope it will be useful to somebody. There will actually be a question at the end.

      So, I got my big disk back today.
      Plug it in, and the finder tells me:
      "You have inserted a disk containing no volumes that Mac OSX can read.
      To continue with the disk inserted, click Ignore."
      So I click ignore.

      I try using the EXTfsmanager  preference pane to mount the disk and get
      Error: 0x1FFFFFFF.
      This suggests, that maybe the file system is bad, so, I run fsck on it.

      david% sudo fsck_ext2 -f /dev/disk2s3
      e2fsck 1.35 (28-Feb-2004)
      Pass 1: Checking inodes, blocks, and sizes
      Pass 2: Checking directory structure
      Pass 3: Checking directory connectivity
      Pass 4: Checking reference counts
      Pass 5: Checking group summary information
      Graham: 47368/61063168 files (14.6% non-contiguous), 112403599/122097106 blocks

      Yes, the disk is VERY (too) full! But at least it showed no errors.

      Then try to mount it manually.
      mount_ext2 /dev/disk2s3 mnt

      And I can see the files on the disk in mnt from the command line. Yea!

      Now try to get the finder to see it:
      disktool -r

      Nope, disk does not show up in the finder. Unfortunately the application
      I want to use to process this data  apparently can't see the disk unless the finder sees it.

      So, lets try the ExtFSManager pref pane again. No good, it
      gives me the Error: 0x1FFFFFFF still.

      So I read the ReadMe again and find:
      " If you re-format an existing partition as Ext2, then that partition may fail to automount in the future. This is because re-formating does not change the partition type in the partition header of the disk."

      Ouch, I'll bet this is my problem.

      Using plist I find:
      /dev/rdisk2  map block size=512
         #:                 type name                  length   base      ( size )
         1:  Apple_partition_map Apple                     63 @ 1       
         2:           Apple_Boot eXternal booter        17408 @ 64        (  8.5M)
         3:            Apple_UFS Apple_UFS_Untitled_2 976776848 @ 17472     (465.8G)
         4:           Apple_Free                            0+@ 976794320

      Sure enough. When I sent him the disk it was formatted as one
      large apple UFS file system (which he could read from his linux box, but not
      write to).  He must have newfs'ed the disk, but not repartitioned it. Haven't
      been able to contact him to confirm this yet. I'm not brave enough to try
      using pdisk to relabel the partition as ext2, at least not until I have the data off it
      Guess I'll run rsync -rul on it tonight to a volume the finder can mount.

      Bottom line is I think this is going to work,  I started rsync'ing the ext2 volume to an HFS+
      volume and can read the files in the finder from the HFS disk.  I'll find out probably tommorow if it actually copied all the files properly
      Let this be a warning to other users of this fine software - if you want the finder to be able to see the disk make sure you partition it as an ext2 volume.

      Does my analysis that the finder can't see this disk because it is an ext2 filesystem
      on a disk partition that my mac still things is ufs sound correct?

      Thanks,  I owe you a (virtual) beer, or something

      • martin langhoff

        martin langhoff - 2004-06-27

        No need to worry. Mount the partition manually as you've been doing. While the Finder won't see it as a mounted partition, it will see it as a "Folder".

        Outside of the fact that you'll have to deal with mount/unmount, it is a fully functional mountpoint at the unix level. The finder just doesn't know it's a different drive. You can probably survive that ;)



      • Brian Bergstrand


        I think you hit the nail on the head. This is a limitation of the system disk manager. Like I said in the ReadMe, the hint is actually literal.

        Not much you can do other than reset the type as Ext2 using pdisk, or re-format the whole drive.


      • Charles Simpson

        Charles Simpson - 2004-06-29

        Actually, I'm not sure that this is the problem.  I stumbled on this thread having the _exact same problem_, down to the LaCie BigDisk and everything.  The drive was actually partitioned and formatted under a Linux box, so I would imagine that it had the proper information.

        Like the parent, I managed to mount the drive to a folder and proceed as normal (copy all of the data off onto a drive that OSX natively recognized), but couldn't get it recognized at all using any of the GUI tools.

        Interestingly, while the drive was attached via firewire and mounted, I wasn't able to get any other firewire drive to be recognized either.  To add another drive to copy to, I had to first umount the ext2/3 drive, plug in the HFS drive, have it be automounted, then remount the ext2/3 drive.

        I got the data off, but figured someone else might be interested if they had the same problem.  For information, I was using a 500GB LaCie BigDisk with 224 GB filled on a dual 2GHz G5, OSX 10.3.2, extfsx v1.2.

    • dknightd

      dknightd - 2004-06-27

      No worries. I got the data off the disk, then reformated it.


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