Copied files on new WD drive, size and size on disk are different

[tkmops]

Why does my new WD external 4TB drive, after copying some files to it, show size:45.3GB, and size on disk:103GB?

The drive that the files were copied from show size:45.3GB, and size on disk:45.5GB.

I've called WD tech support, they have no idea of why that is.

I've used many WD external drives over the years, this is the first time this has happened.

Anyone know?   

Win 7

[patio]

Not sure what you did...how did you copy/move those files  ? ?

[Lisa_maree]

Western Digital ship their drives formatted exfat. This is so they work on Mac's and PC's. Exfat uses a different cluster size to NTFS on windows 7

Exfat is 128KB per cluster and NTFS is 4KB per cluster.
For example :So if you have a 16KB file saved to an NTFS drive it will use 4 clusters even. If the same file is saved to an exfat drive it will use one  128KB cluster wasting 112KB.

So normally exfat formatted drives use more drive space to store the same files as fat and NTFS. As it is only a few GB's for every TB of data it is a small price to pay for universal compatibility.

[tkmops]

I copied the files the normal way, right click on the files, drag to new drive and click 'copy' I told the WD tech that the drive was formatted exFAT, and if that was the issue...he said 'no'. But, I think it is, as all my other drives are NTSF. Maybe I need to save my current data(not very much as the drive is new), format to NTSF, then copy the saved files back? 

[Lisa_maree]

The reason WD ships the drive as exfat is it is larger than the 2TB  limit for NTFS. If you want to format the drive NTFS you will either need to set it up GPT which is only supported by windows 7 SP2 and later PC operating systems and then make a partition of 4TB or split the drive into 2 partitions of 2TB.

What is the problem with using exfat ?

I'm amazed after i explained  about cluster size etc in my last post and you still believe the WD tech   

[BC_Programmer]

The reason WD ships the drive as exfat is it is larger than the 2TB  limit for NTFS.

The main reason a drive would come pre-configured with it is likely because it is the most generally compatible and supported across operating Systems now. Windows doesn't support Ext4 or HFS+ and Mac OS cannot write to NTFS for example. The 2TB Limitation is on MBR, and applies regardless of the File System limitation. Their External Drive already uses GPT if it has a single 4TB partition because of this. Neither NTFS nor even FAT32 have a 2TB size limitation. (in fact, FAT32 can go to 8TB, but Windows arbitrarily disallows you from formatting anything larger than 32GB as FAT32)

What is the problem with using exfat ?

I think they described that pretty well in their OP. In their instance, Data is consuming twice the disk space of it's actual content. It could be due to a lot of small files bringing up the amount of slack space, or it could be because the cluster size came configured very large from the factory (ExFAT allocation unit sizes can go from 4KB up to 32MB). It's also possible that during the copy operation the new data ended up getting preallocated in larger chunks by having the physical data length field far exceed the real data length field. a disk check might fix that.

Personally, I would only use ExFAT on smaller removable drives. And only if I don't intend to store anything that matters on it for very long, because in my experience I have found ExFAT is a great way to approximate the data reliability of using 360K floppies in a magnet factory.

[artbuc]

So, if you buy a WD external drive with exfat, can you reformat it to NTFS?

BC, why is the exfat format unreliable? Thanks.

Edit: BC, I found this. Is this why exfat is unreliable?

“exFAT is a good choice if you often work with Windows and Mac computers. It could make transferring the files between those two operating systems much easier because you don’t need to back up and reformat each time. Besides, this file system inherit something popular and great from FAT32 including the incredible compatibility. But exFAT (like other FATs) lacks a journal, and so it easily gets corrupted when the volume is not unmounted or ejected in a proper way.”

[Lisa_maree]

But exFAT (like other FATs) lacks a journal, and so it easily gets corrupted when the volume is not unmounted or ejected in a proper way.”

Yes this is correct. Without the journal if both copies of the fat table get corrupted, which can happen if you unplug a fat drive when it is writing. Could cause the directory structure to get corrupted making access to the files difficult. This is why windows and mac's if you move the mouse over the usb connection say if the drive is safe to disconnect. If you disconnect any drive regardless of format when writing or in the case of an SSD drive when reading or writing there will be data loss. Ntfs is just less likely to corrupt as badly and  easier to recover from.