Cannot Erase a 64Gb exFat SD Card with Disk Utility | OS Mojave

I’ve got a microSD card in an SD adaptor that I accidentally left in during the Bootcamp installation and now it is formatted as exFat rather than Fat-32. I tried erasing it and changing the format, but it says:

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I looked at a couple pages on here and typed in some console commands but they didn’t do anything so I’m writing my own question. Any suggestions are greatly appreciated. Thanks. Also, here is the info:

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EDIT: I think I found out why it won’t erase – there is a windows NTFS format inside the disk, named disk2s1.

Files on external drives executable by default with exFAT or NTFS under Ubuntu

On Ubuntu, if you use (external) drives formatted as exFAT or NTFS, i.e. not ext4 or something made for the UNIX world, you may end up with a situation where all files are executable.

This is because the file systems may have other concepts of permissions, or none at all. And it is to faciliate sharing between multiple computers. That makes sense.

Usually, you can even adjust this behavior in the mount options. But with the default options, the drives are often auto-mounted with the behavior described above.

Could you consider this a security risk? Especially if it comes to non-technical users, who will only ever use the default mount options (e.g. your grandma whom you switched to Ubuntu).

You could probably say it very much depends on the contents of the drive. But why introduce the risk?

running into bad clusters after chkdsk on exFat Micro SD card

This is a Sandisk 128gb ( leave this link – its not an ad .Specific card indicates other paras like memory channels , write speed etc card I am using on an Android Nougat device.

This is the 2nd time the card had corruption issues. 1st one I bought got Write Locked . Present Replacement was provided
The card has a lot of bad clusters. 2 things got me to sniff this :

  • whatsApp directory ( which had a bind to whatsapp dir on internal ) : the image directory can no longer be written to
  • Phone randomly reboots and next time exFat partition is not mounted ( I used app2sd and partitioned the card to ext4 10gb to link my apps and rest if exfat )

ran a chkdksk on windows 7 and it would autoterminate on initial run & persisting on running gave me repeated message “# cluster moved for file ” ( cant recollect exact verbiage ). It could Never complete it but aborted with the message . “corruption found in card “

questions :

  • How do I know if there is logical or physical bad cluster. Any tool / test ?
    Here’s something I did – that made me think logical. I removed the images directory ( which was write locked and so as long as the binding was on , whatsapp images could not be downloaded. Once I switched off folder mount tool that enforced this, it would work ) after moving the contents to dir2 and renamed dir2 to original dir. after del the original dir. Now for sometime whatsapp binding would work and the same problem came again . So I tend to think but need confirmation.
  • I am thinking of salvaging the contents of exfat partition and then format partition and instead create 2 ext4 partitions ( or FF2S. Tell me which is better) . One is for less write apps. My photos etc here and other smaller one just for whatsapp and then copy back contents to relevant partitions.

If I do this. There is no out of box support for ext4 partitions for android ( isn’t ,pl confirm) ? how do I auto mount without 3rd party utils ( fstab ? ) How do I auto mount the extra ext4 - fstab ? Will this help avoid the above problem ?

  • While I still have the corrupt block partition is there ANY other tool that will run till the end and identify all bad blocks so they can be kept aside .I tried aparted for android which runs fsck ( exFat sub ) and the report came normal in < 1 min .

Can’t see newly created parition (and formatted as ExFat or NTFS) in Bootcamp (Windows 7)

I’m trying to resize my Bootcamp partition and finally shrunk my AFPS partition smaller and formatted the new partition to NTFS (and later to ExFAT) in hope to be able to see it in Windows and merge it with Bootcamp (Since I can’t do it in macOS due to my Boocamp partition being NTFS) but I can’t see it in Windows in any program I try to merge them. I just see Bootcamp partition and one big “Apple” one which in fact should be three.

(I’m Using Mojave)


Brand new external hard drive formatted exFAT is mounted read only

I bought a new HDD, formatted as exFAT with mac. I moved files from my laptop to the HDD (moved, I mean, I also deleted them). It happened with a directory it got stucked. I quit the process of copying that directory. I tried to trash and erase trash. I could not erase it. I tried eject from Finder. It could not. I unplugged – when there were no process active.

I tried to plug, and could not mount. I discover apple run fskc automatically. I kill the process, used disktutil to mount the volume, unmount and eject.

I tried to plug and mount and again. Now the volume is mounted, but Read only. S.M.A.R.T. not verified.

So I launch fskc – I don’t know when it will finish, there are (estimated) about million files, HDD is 4T.

I m confident disk is ok, since brand new.

Please advice on how get rid of read-only and steps to mount exFAT external HDD properly in mac, want to prevent automatic fskc – also because fskc is taking forever, and not sure it could repare anything if in read-only mode. FSKC is stucked at checking system hierarchy:

    diskutil list  /dev/disk0    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      GUID_partition_scheme                        *500.3 GB   disk0    1:                        EFI EFI                     209.7 MB   disk0s1    2:                  Apple_HFS Macintosh HD            499.4 GB   disk0s2    3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3 /dev/disk1    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:      GUID_partition_scheme                        *4.0 TB     disk1    1:                        EFI EFI                     209.7 MB   disk1s1    2:       Microsoft Basic Data myHDD                 4.0 TB     disk1s2    sudo fsck_exfat /dev/disk1s2 fsck_exfat: Opened /dev/rdisk1s2 read-only ** Checking volume. ** Checking main boot region. ** Checking system files. ** Volume name is luigi4T. ** Checking upper case translation table. ** Checking file system hierarchy. 

Mac OS 1.9.5

`diskutil list` shows type Windows_NTFS, but `Disk` shows type ExFAT. So What is the type?

I just bought a new external ssd drive (connected to USB3 port of Macbookpro). and then run

$   diskutil list /dev/disk1 /dev/disk1 (external, physical):    #:                       TYPE NAME                    SIZE       IDENTIFIER    0:     FDisk_partition_scheme                        *480.1 GB   disk1    1:               Windows_NTFS TOSHIBA SSD             480.1 GB   disk1s1 

It shows Windows_NTFS. And then I launched Disk It shows me USB External Physical Volume • ExFAT. I am not going to paste the screenshot, but this is what it displays. This is very weird.

How to tell the true file system type? Thanks.

Btw, I know I can reformat it with Disk, but I just want to know the current type in this question. Thanks a lot.

ExFAT file modification time issue

I’ve encountered a weird issue with rsync (without -c) copying already synched files over and over again to an ExFAT formatted drive.

The involved files are images from an automated image extraction process from .docx word documents and have a modification time of Jan 1, 1980 00:00:00 which is the minimum time supported by the ExFAT timestamp format.

After a rsync -a src dst the destination files on ExFAT have a modification time of Jan 1, 1980 02:00:00.

It looks like the minimum time supported by my OS X ExFAT driver is off by two hours.

And this is the reason that causes rsync’s quick comparison algorithm to believe the files are different.

The following test seems to confirm this:

# create a 10Mb ExFAT disk image: hdiutil create -size 10m -fs ExFAT -volname EXFATTEST exfattest.dmg  # attach the diskimage hdiutil attach exfattest.dmg  # create a test file with a creation time of Jan 1, 1980 00:00:00 touch -t "198001010000.00" /Volumes/EXFATTEST/test.txt ls -lT /Volumes/EXFATTEST/test1.txt  -rwxrwxrwx  1 user  staff  0 Jan  1 02:00:00 1980 /Volumes/EXFATTEST/test1.txt #                                   ^^ off by two hours  # try a file with 3am touch -t "198001010300.00" /Volumes/EXFATTEST/test2.txt ls -lT /Volumes/EXFATTEST/test2.txt -rwxrwxrwx  1 user  staff  0 Jan  1 03:00:00 1980 /Volumes/EXFATTEST/test2.txt #                                   ^^ works as expected   # unmount the disk image hdiutil detach /Volumes/EXFATTEST/ 

An equivalent test on Linux does not show this error:

truncate -s 10M exfattest.img mkfs.exfat exfattest.img mkdir /mnt/EXFATTEST/ mount -o loop exfattest.img /mnt/EXFATTEST/ touch -t "198001010000.00" /mnt/EXFATTEST/test.txt ls --full-time /mnt/EXFATTEST/test.txt rwxr-xr-x 1 root root 0 1980-01-01 00:00:00.000000000 +0100 /mnt/EXFATTEST/test.txt #                                  ^^ correct modification time umount /mnt/EXFATTEST/ 

My simple solution is to update the source files’ creation time using touch.

However, I’d like to know if this is really a bug and if someone can reproduce this error on newer OS X releases since Apple doesn’t allow my still perfectly fine running early 2008 iMac to be be upgraded 😉

I’m still on El Capitan:

sw_vers ProductName:    Mac OS X ProductVersion: 10.11.6 BuildVersion:   15G22010 

External SDD (exfat) shows different size from mac os disk

I have an external ssd with exFat filesystem. I’ve copied some files from mac to it, no other operations. When I go checking with disk utility it shows:

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about ten times the size of original mac os folder. Same is reported by du. When I go check with finder cmd-I, it shows:

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same size of original but 10x on sdd. How comes?