Kopia UI: External HDD almost immedately shows up on Windows 11, but take quite some time on Linux Mint 22

General Topics
1

I’m using Kopia and Kopia-UI to backup my data on two machines, one being Windows 11, the other Linux Mint 22 to a single repository the same external HDD. Everything works fine.

However, out of curiosity:

  • When I attach the external HDD to the Windows machine, wait for the HDD to be ready, then start Kopia UI, the repository appears almost immediately in the Kopia-UI tray icon.
  • When I attach the external HDD to the Linux machine, wait for the HDD to be ready, then start Kopia-UI, it takes quite some time until the repository is shown in the Kopia-UI tray icon. Kopia-UI shows “Initializing…” until then. I can see disk activity while duting this time.

Is there anything I can do so that it takes less time for the the repository to become ready? Linux is my main machine, so I much more often need to backup from this machine.

Thanks
Peter

2

What file system did you use?

3

The partition on the external HDD is formatted as exfat. It also has the mstfdata flag set (not sure if that matters at all).

4

Yeah… I’d suspect, that the exfat driver is not the fastest on Linux. If there’s significat disk i/o going on, that would be my guess.

5

It’s not that the backup process itself seems to be significantly slower in the Linux machine. Both snapshots are some 400 GiB large. And the number of directories and files are also similar. It’s only the time the initialization takes.

There is not really an alternative to using exfat when I want the HDD to be used on Linux and Windows, right? And there is no setting that was backwards on the Linux machine. I can live with this.

Thanks

6

And that’s perfectly fine. Its not the transfer rates of rather big chunks, which is the issue, but probably more the latency when dealing with the mounting. exFAT is not a journaling file system and the exFAT itself has been designed decades back and is rather inefficient.

7

This is very bad choice for this job. ExFAT is ancient and primitive. Do some Google if you want to know more. Risk of data corruption is high. It is only good for simple file exchange between systems - nothing more really.

Linux should deal with NTFS very well, especially since kernel 7.1. when a ground-up rewrite of the in-kernel NTFS driver was introduced, bringing native, high-performance read and write support. It would be much better choice supported natively by both worlds.

8

Thanks, I’ll give NTFS a try if kernel 6.8 is suitable (I’m using Linux Mint 22 which is at kernel 6.x)

Given I’d format one of the HDDs with NTFS, can I simply copy the repository from the exFat HDD to the NTFS HDD?

9

Kernel 6.8 does support NTFS as well, though it is not using the latest and greatest drivers. Give it a try.

Yes you can copy/move repository between disks - no problem.

10

I have shrunk the exFat partitions, created new NTFS partitions on both of my USB HDDs. Then copied the repositories from the exFat to the NTFS partitions (cross over to), then verified the snapshots on both NTFS partitions.

Working with the NTFS partitions since a few day. Everyting ok, so far.

ExFat partitions will be deleted, once I’m confident working with the NTFS does not cause any problems.

Side remark: It was nontrivial to shrink the exFat partitions. Both Gparted on Linux and Diskmanager of Windows 11 refused to do it. I had to install “DiskGenius free”.