Can't unmount disk

Due to inability to boot up, I am trying to erase the hard disk on my Mac pro Lion 10.7. I keep getting the message "couldn't unmount disk" Anybody help?

Fourbrick said:

Due to inability to boot up, I am trying to erase the hard disk on my Mac pro Lion 10.7. I keep getting the message "couldn't unmount disk" Anybody help?

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Well, you've not given us much information, e.g. model/year of your MBPro, backup(s) available (e.g. bootable DVD, bootable USB, etc.), or what you have tried so far. For starters, take a look at this ARTICLE to see if any of the 'bootable' suggestions there are of help, then post back your progress. Good luck - Dave

Fourbrick said:

Due to inability to boot up, I am trying to erase the hard disk on my Mac pro Lion 10.7. I keep getting the message "couldn't unmount disk" Anybody help?

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Are you trying to boot to your recovery partition first and run Disk Utility? (Restart and press command plus r to get into recovery. Go to Utilities, Disk Utility.)

chscag said:

Are you trying to boot to your recovery partition first and run Disk Utility? (Restart and press command plus r to get into recovery. Go to Utilities, Disk Utility.)

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Thanks for the help guys. I was trying to unmount the wrong disk.:Blushing: Have sorted the problem by saving the required information to another Apple, and then erasing the contents of the Mac Hard disk, and then reloading Lion. Everything now back to normal. Thanks again for your help.

Hello. I know this conversation seems to be close, but thought I'd try to post here. I'm having a problem unmounting an external hard drive. I have a 2010 iMac with a 1.5 TB Seagate external hard drive I use for Time Machine as well as other backups. I cannot transfer files to/from this hard drive anymore, and Time Machine will no longer work. I can see the drive in Finder, but some times the folders appear to be empty of files, and sometimes I can see the files but cannot access. Disk Utility states the disk needs to be repaired, but when I try to repair the disk, "unable to unmount for repair" is stated. I've tried to unmount through disk utility as well as through Terminal. I've tried to unmount the entire disk as well as the individual partitions. Any suggestions would be great. Thanks.
Example of what I've tried in Terminal. (sorry if my computer speak is wrong. Not really a computer expert)
#: TYPE NAME SIZE IDENTIFIER
0: Apple_partition_scheme *1.5 TB disk1
1: Apple_partition_map 32.3 KB disk1s1
2: Apple_HFS HLH1.5TB 1.5 TB disk1s3
Macinto9e3bfb3c:~ howardhonig$ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 999.3 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: Apple_partition_scheme *1.5 TB disk1
1: Apple_partition_map 32.3 KB disk1s1
2: Apple_HFS HLH1.5TB 1.5 TB disk1s3
Macinto9e3bfb3c:~ howardhonig$ diskutil unmountDisk /dev/disk1
Unmount of disk1 failed: at least one volume could not be unmounted
Macinto9e3bfb3c:~ howardhonig$ diskutil unmount /dev/disk1s1
disk1s1 was already unmounted
Macinto9e3bfb3c:~ howardhonig$ diskutil mount /dev/disk1s1
Volume on disk1s1 failed to mount
If the volume is damaged, try the "readOnly" option

Hello. I know this conversation seems to be close, but thought I'd try to post here. I'm having a problem unmounting an external hard drive. I have a 2010 iMac with a 1.5 TB Seagate external hard drive I use for Time Machine as well as other backups. I cannot transfer files to/from this hard drive anymore, and Time Machine will no longer work. I can see the drive in Finder, but some times the folders appear to be empty of files, and sometimes I can see the files but cannot access. Disk Utility states the disk needs to be repaired, but when I try to repair the disk, "unable to unmount for repair" is stated. I've tried to unmount through disk utility as well as through Terminal. I've tried to unmount the entire disk as well as the individual partitions. Any suggestions would be great. Thanks.

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My simple answer to your problem: Replace the drive, it's defective. There is absolutely no point in trying to repair a drive that won't even dismount. And even if you could do repairs, the drive will likely fail when you need it most. ;D

I plan on replacing the drive. However, I would like to get some files off the drive if possible. Any ideas how to do that? The drive will not let me transfer files. I get an error message.
Thanks

There is software that you can use to "try" to extract data from that drive, however, that kind of software is generally expensive. "Disk Warrior 5" is about the best at doing what you need.

Thanks