Why.

I do a backup once a week in Win 11 of all my partitions as its the only OS that has decent programs like Macrium reflect and Hasleo Backup Suite.

I copy the backup images from external hard drive A to external hard drive B and verify the copy with teracopy. But recently some of the copies have been failing to write to the HDD, the error is failed to write error:1 in terracopy.

So I decided to see if it was terracopy at fault and copied a 51gb image using Explorer in Win 11 and it got to about 62% and said MS-DOS error. More testing from command line I tried xcopy which seemed to copy the file but when doing a FC /B in terminal it said the original was larger.

So then I tried robocopy to copy the file and it got to about 81% and said Invalid Function re-trying.

This doesn't happen in Linux with the same hardware. At first I thought the disk was on its way out with bad blocks. But copying the file in Linux completes successfully and the hashes match. Running a FreeFileSync comparision says no differences.

Is this a Windows problem with the copy function? Any ideas?

Have you tried disabling any anti-virus software whilst doing the copy? The other thing to look at is the possibility of flaky RAM. A comprehensive memory test might be a good idea. Presumably you’ve done a full scan of the external drive. Other possible failure causes, such as access problems, wouldn’t cause failure half way through a copy.

In the end, if it copies OK in Linux then use Linux to do the copy.

I can't really answer the Why?

But I do something similar except I do a Monthly/Weekly/Daily Grandfather/Father/Son backup using Macrium to an external drive attached to a WD NAS and use SyncBackPro to copy it from the HDD to the NAS later on in the day without problems.

In reply to a post by Banger:

Is this a Windows problem with the copy function? Any ideas?

Windows copy, xcopy, robocopy are reliable and I have personally used to copy exabytes of data.

I have colleagues that use teracopy as a GUI extension for the file manager, and I don't know if this implements its own copy function or uses the operating system. I wonder if your source file system is FAT32 or NTFS, as you are reading also from Linux?

Are you copying to a USB drive or to a network drive?

Many Windows machines run third party (non Microsoft) antivirus products, and some of these always assume any large data transfer is likely malware trying to get your info. It could be something like that. Most third party security products can't be turned off, and have to be uninstalled to test, often painful if you want to put them back after.

In reply to a post by jchamier:

In reply to a post by Banger:

Is this a Windows problem with the copy function? Any ideas?

Windows copy, xcopy, robocopy are reliable and I have personally used to copy exabytes of data.

I have colleagues that use teracopy as a GUI extension for the file manager, and I don't know if this implements its own copy function or uses the operating system. I wonder if your source file system is FAT32 or NTFS, as you are reading also from Linux?

Are you copying to a USB drive or to a network drive?

Many Windows machines run third party (non Microsoft) antivirus products, and some of these always assume any large data transfer is likely malware trying to get your info. It could be something like that. Most third party security products can't be turned off, and have to be uninstalled to test, often painful if you want to put them back after.

Well I have run memtest86+ and RAM passed as Tiny suggested.

The scenario is I have 2 x USB3 docks with 4 hard drives, 2 drives are brand new 25 hours power on time and 2 drives are donated. The donated drives have had a fair amount of use and have been thoroughly checked with Victoria and HDDScan as well as windows chkdsk bad block scan.

I run Macrium and Hasleo to HDD A then copy the resulting images to the other 3 drives. Teracopy has it's own buffer size so I am not sure if it uses the MS-DOS copy function. As the error (invalid function) is the same as DOS I suspect it does.

Next week when I do a backup I will disable defender to see if it's interfering with the copy process. All the drives are NTFS in answer to your question.

I might have to do the backup in Windows then do the copies in Linux as Tiny said.

You can still do the copies in Windows using WSL.

is drive b, a new drive, or in a new enclosure ?

if it is, can you confirm the controller ?

Drive B is in an ASMedia dock. Drive A is in a JMicron dock both Wavlink. Curious thing no problems with Linux.

In reply to a post by Banger:

Drive B is in an ASMedia dock. Drive A is in a JMicron dock both Wavlink. Curious thing no problems with Linux.

Jmicron usb to sata chips can fail on large transfers, its a known issue, and something which i've witnessed my self with a 60gb file transfer

Well its backup day. Surprisingly I have had no problems copying files between drives and verification. The only difference with the copy on teracopy I copied whole folders instead of single large files telling teracopy to skip existing files. Very strange.