Erasing external drive still leaves a hidden? partition

Discussion in 'OS X El Capitan (10.11)' started by ilandmac, Mar 4, 2016.

  1. ilandmac macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #1
    Running El Cap,

    Erased an external previously used drive for another purpose.

    Disk utility shows only one partition, ok

    but it also shows I have 79 files left on the drive and tells
    me I only have 95% of the drive capacity available.

    I'm used to deal with the EFI thing but that's only like 200 megs

    Went thru a few used disks and I get the same story.

    So I just started a secure wipe but that takes ages among other things...

    Any clues ?

    Thanks
    ilandmac
     
  2. DeltaMac macrumors 604

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #2
    Be sure that you select the device line (Manufacturer's model and size info line) when you erase the drive.
    If your select just the drive partition line, you only erase THAT partition, and not the entire drive.
     
  3. BLUEDOG314 macrumors member

    BLUEDOG314

    Joined:
    Dec 12, 2015
    #3
    could nuke the partition table by going into terminal and type diskutil list to get the drives identifier, like disk3 or whatever it may be. Then type diskutil unmountdisk disk3, then type cat /dev/zero > /dev/disk3, hit enter, itll drop to a blank line. it only has to run for a second, then press control c to stop the process. When you go into disk utility now the disk should show up as uninitialized.
     
  4. ilandmac thread starter macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #4
    Hello bluedog,

    Tried but at the last command I get "permission denied" ...

    this is what I see, "Main" pic is the first line in disk utility, untitled is the blank formatted with GUID

    Main.jpg Untitled.jpg
    --- Post Merged, Mar 5, 2016 ---
    Deltamac,

    I do erase from the device line, "HGST..." but still get the formatted "untitled" volume with 1,38 gigs missing
     
  5. DeltaMac macrumors 604

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #5
    But then, it is only 1.38GB, out of 6TB, some .023% of the total available :D

    And, you can try the terminal command again, beginning with a sudo
    by
    If your drive identifier still is listed as disk15, then you would use
    Code:
    sudo cat /dev/zero > /dev/disk15
     
  6. dsemf macrumors regular

    Joined:
    Jul 26, 2014
    #6
    The 1.38 GB is most likely the inode table.

    Do a df command in terminal. The iused, ifree and %iused columns display the inode information.

    Code:
    Filesystem                                       1G-blocks Used Available Capacity   iused    ifree %iused  Mounted on
    /dev/disk1                                             232  188        43    82%  49490705 11492685   81%   /
    devfs                                                    0    0         0   100%       638        0  100%   /dev
    map -hosts                                               0    0         0   100%         0        0  100%   /net
    map auto_home                                            0    0         0   100%         0        0  100%   /home
    localhost:/sSagFJKxeCV_1WXXuxUbwn                      232  232         0   100%         0        0  100%   /Volumes/MobileBackups
    //xxxx%20yyyy@zzz._afpovertcp._tcp.local./Data      1861 1849        11   100% 484891740  2962606   99%   /Volumes/Data
    /dev/disk3s2                                          1860 1849        11   100% 484815954  2954414   99%   /Volumes/Time Machine Backups
    
    I would expect that a 6TB disk would have a very large number of inodes defined.

    DS
     
  7. IowaLynn macrumors 6502a

    IowaLynn

    Joined:
    Feb 22, 2015
    #7
    Some external cases lack support to format 6TB can you try it in another case? different interface, Mac or even older OS X?
     
  8. ilandmac thread starter macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #8
    Hello,

    Deltamac, tks for your help this is why went with the command :

    cs-Mac-Pro-2:~ cl$ diskutil unmountdisk disk15
    Unmount of all volumes on disk15 was successful
    cs-Mac-Pro-2:~ cl$ sudo cat /dev/zero > /dev/disk15
    -bash: /dev/disk15: Permission denied
    cs-Mac-Pro-2:~ cl$

    IowaLynn, Hi this is what df command gives out :
    df.jpg



    And this is what I find disturbing, these folders & files after a full format ... :



    Disk Utility.jpg


    Thank you all for your help

    ilandmac
     
  9. KALLT macrumors 601

    Joined:
    Sep 23, 2008
    #9
    Can you try it with this as well:
    Code:
    diskutil unmountdisk diskX
    sudo dd if=/dev/zero of=/dev/diskX

    Do you have another system available? Windows, Linux or even an older version of OS X upon which you can try this?
     
  10. DeltaMac macrumors 604

    DeltaMac

    Joined:
    Jul 30, 2003
    Location:
    Delaware
    #10
    Post #8 is showing an older version of Disk Utility, not from El Cap.

    @ilandmac - What happens in that version of Disk Utility, Select the device, then go to the Partitions tab?
    Now, click the dropdown for Partition Layout, and choose 1 Partition.
    Name the partition if you like.
    Click the Apply button, and then continue with the partition.
    Does THAT process finish any differently?

    Just a general question for anyone that reads this, and who might know the answer:
    How much space is used after creating a new partition on a really large hard drive such as the OPs (6TB)?
    (I don't have anything over 2TB. I used to think that was a lot of space, too :D )
     
  11. ilandmac thread starter macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #11
    Hi Kallt

    I have a couple of Mavericks machines lying around, I'll give it a try this weekend.
    Tks for your help!

    ilandmac
    --- Post Merged, Mar 5, 2016 ---
    You are right, I'm mostly using the Yosemite version of Disk Utility because the one in Capitan
    is barely usable in my opinion. In this case I used both so as to be certain of these remaining
    files.

    I did do what you're suggesting, in all ways and manners that I could think of but to no avail.

    So an OS X erase & reformat (in all its flavours) , where they tell you this will completely wipe
    out a drive (short of the EFI issue of sorts..) is just not effective, to be polite.

    Best
    ilandmac
     
  12. BLUEDOG314 macrumors member

    BLUEDOG314

    Joined:
    Dec 12, 2015
    #12
    I find it very odd that you get permission denied still with sudo, did it prompt you for an admin password? fwiw, try booting into your recovery partition and doing my original suggestion again (or KALLT's would work as well). This should rule out any kind of permission issues since you're not in your user environment, and you wouldn't need to use sudo even.
     
  13. HenryAZ macrumors 6502

    HenryAZ

    Joined:
    Jan 9, 2010
    Location:
    South Congress AZ
    #13
    sudo diskutil partitionDisk /dev/disk4 GPT jhfs+ VolumeNameOfYourChoice 100%

    should do it. Just make sure to get the correct disk ID, by running diskutil list first (I used /dev/disk4 in this example, but get the correct number for the disk you wish to wipe)
     
  14. ilandmac thread starter macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #14
    Hello Bluedog,

    will try that. Mac is tied up right now for the next 30 hours sot I'll wait till then for a reboot. Tks!

    Henry, will try your solution manana. Tks!

    ilandmac
     
  15. sigsegv, Mar 6, 2016
    Last edited: Mar 6, 2016

    sigsegv macrumors newbie

    sigsegv

    Joined:
    Nov 17, 2012
    Location:
    Seoul
    #15
    Also be aware that you will get a whole lot of Spotlight index files (empty) on a freshly formatted volume. That would account for most of the 78 files.

    Code:
    mini:~ $ diskutil eraseDisk JHFS+ Emptydisk disk3
    Started erase on disk3
    Unmounting disk
    Creating the partition map
    Waiting for the disks to reappear
    Formatting disk3s2 as Mac OS Extended (Journaled) with name Emptydisk
    Initialized /dev/rdisk3s2 as a 1 TB case-insensitive HFS Plus volume with a 114688k journal
    Mounting disk
    Finished erase on disk3
    
    mini:~ $ sudo find /Volumes/Emptydisk/
    /Volumes/Emptydisk/
    /Volumes/Emptydisk//.com.apple.timemachine.donotpresent
    /Volumes/Emptydisk//.fseventsd
    /Volumes/Emptydisk//.fseventsd/fseventsd-uuid
    /Volumes/Emptydisk//.Spotlight-V100
    /Volumes/Emptydisk//.Spotlight-V100/Store-V1
    /Volumes/Emptydisk//.Spotlight-V100/Store-V1/VolumeConfig.plist
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/.store.db
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.directoryStoreFile
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.directoryStoreFile.shadow
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexArrays
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexCompactDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexGroups
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexHead
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexIds
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexPositions
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexPositionTable
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexPostings
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexTermIds
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.indexUpdates
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.shadowIndexGroups
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/0.shadowIndexHead
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/Cab.created
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/indexState
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journalAttr.1
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journalExclusion
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.assisted_import_post
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.assisted_import_pre
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.corespotlight
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.health_check
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.live
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.live_priority
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.live_system
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.live_user
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.migration
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.migration_secondchance
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.scan
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/journals.scan/retire.2
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/Lion.created
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.directoryStoreFile
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.directoryStoreFile.shadow
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexArrays
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexCompactDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexGroups
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexHead
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexIds
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexPositions
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexPositionTable
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexPostings
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexTermIds
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.indexUpdates
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexArrays
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexCompactDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexDirectory
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexGroups
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexHead
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexPositionTable
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/live.0.shadowIndexTermIds
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/reverseDirectoryStore
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/reverseDirectoryStore.shadow
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/reverseStore.updates
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/shutdown_time
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/store.db
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/store.updates
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/store_generation
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/tmp.Cab
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/tmp.Lion
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/tmp.SnowLeopard
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/tmp.spotlight.loc
    /Volumes/Emptydisk//.Spotlight-V100/Store-V2/4FC247C5-E07F-4109-864F-C0606673AB6D/tmp.spotlight.state
    /Volumes/Emptydisk//.Spotlight-V100/VolumeConfiguration.plist
    /Volumes/Emptydisk//.Trashes
    
     
  16. ilandmac thread starter macrumors member

    ilandmac

    Joined:
    Mar 25, 2012
    Location:
    Remote island
    #16

    Hi Sigsegv

    Agreed eventually on the # of files, but I cannot see spotlight using 1,38 gig for this. That's like a lot on a supposedly empty drive...
    Plus this info is gathered seconds after formatting.

    Best
    ilandmac
     
  17. sigsegv macrumors newbie

    sigsegv

    Joined:
    Nov 17, 2012
    Location:
    Seoul
    #17
    The spotlight index appears to be created instantly. I ran that only 2-3 seconds after the format.

    The other overhead you might notice is the metadata zone:
    https://developer.apple.com/legacy/library/technotes/tn/tn1150.html#MetadataZone

    I haven't run the calculation but it's entirely plausible that 1,38 G is consumed there - possibly more when you look at the catalog and hot files. At the time that tech note was written (2004) they could account for up to 1.5% of space.

    Apple may have tuned those ratios down a bit over the past 12 years now that we have multi-TB drives and multi-GB files.
     

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