partitioning problem ,showing double the data size ....

[mudh]

I wanted to partition my 1TB hard disk with disk utility , all I had in that disk was 400 GB data so I wanted to partition it into two partitions of 500MB each , I successfully dragged the slider to adjust sizes and started the process, unfortunately there was power cut and I had to restart the comp after which now it show a full partition of 999GB and almost entire partition barring a few MBs is blue , that is , it is showing that almost the entire drive is full with data which is not true, so obviously when I try it doesn't partition and all tabs on the partition page are greyed..... while trying to partition I get this error too :

Partition failed with the error:

Couldn’t modify partition map because file system verification failed.

How should I correct it now ......?

 

[MarkC426]

Do you have a backup of the data (or is this your system disk).
If so I would reformat the drive and create the two partitions.

 

[mudh]

This is my system disk... and all I want is a repair or scan method by which it just starts showing it's correct size ....

 

[MarkC426]

Have you run first aid?
It’s damn bad luck to have a power out during the process...this may have damaged the drive (I highly recommend having a ups).

 

[h9826790]

When the HDD only has a single 1TB partition. The data is not necessary only located in the very first (or last) 500GB space.

When you want to partiton it 2x 500GB. The system will have to move all data together, squeeze them into the 1st 500GB continuous space. Otherwise, can't create the 2nd 500GB clean partition.

I have no idea how to OS to achieve this. But if you have a power outage during the data re-allocation (which should include data copying). Then this may explain why the usage is doubled.

At this point, if you have proper backup. I think you should simply recover from backup, but not continues to work on this HDD which may contain corrupted data.

If you have no backup, then you should try to copy out all the data to a backup drive. Then check if the backup data is OK.

If yes, format that 1TB drive, partition it into two 500GB partitions, then recover from your newly created backup.

If no, and you need those data. You should shutdown the Mac and get the HDD out ASAP, and don't power it up as boot drive again until you recover all the data from it.

 

[mudh]

A basic clarification.........As you have mentioned
"If yes, format that 1TB drive, partition it into two 500GB partitions, then recover from your newly created backup."

If I create a new backup would it not be of the same double size due to corruption with all the corrupt space? if I recover from the newly created backup will it not copy all the corrupt sectors again or , is it so that somehow I can create a backup of only system files including all my softwares ?I mean if my backup is again of 999 gb how will it fit in 500....or by backup you mean something else other than cloning ? can this backup only be of system files and not the complete partition with non-system data ....? and if yes , should I use time machine for it ?

 

[h9826790]

A basic clarification.........As you have mentioned
"If yes, format that 1TB drive, partition it into two 500GB partitions, then recover from your newly created backup."

If I create a new backup would it not be of the same double size due to corruption with all the corrupt space? if I recover from the newly created backup will it not copy all the corrupt sectors again or , is it so that somehow I can create a backup of only system files including all my softwares ?I mean if my backup is again of 999 gb how will it fit in 500....or by backup you mean something else other than cloning ? can this backup only be of system files and not the complete partition with non-system data ....? and if yes , should I use time machine for it ?

The newly created backup should be normal size. However, you really have to check if the files are not corrupted.

 

[DeltaMac]

If you had a 1TB partition, with 400GB used, then had a failed split of that 1TB into 2 partitions -- the data should still be there.
Back the drive up, in its present condition, to another external drive. You SHOULD still see the 400GB used on the backup drive.
That's a backup of your internal, so boot to another system, on another drive. I don't think you should trust the recovery system on your internal drive, so boot to some other drive, or a macOS bootable installer.
Erase the 1TB internal drive (the WDC device, not just the partition, as that is likely corrupted.) Reinstall your system, which will be convenient if you have booted to a bootable macOS installer - just continue with that macOS install after formatting the drive.
And --- restore your apps and data from your backup.

 

[mudh]

In the image below I have selected all these folders of the problematic Machintosh HD partition and found it to be around 400 GB unlike the size it is showing of 900 GB, does just copy pasting these folders mean that you have copied the entire system , or restoring does something more or is anything more left to be installed or copied ?

, in case you are not able to open the image I am talking about the folders from 'Applications to users' that we see after opening Machintosh HD.....

 

[DeltaMac]

You can display the other (hidden) folders and files in your system. If you have a fairly recent system (Sierra or later, I think), you can press Shift-Command-. (that's a period!).
Each time you press those same 3 keys, the hidden files will toggle on and off.