Support for ReFS on USB drives

[Brad-Translucent]

I am using large (12TB) USB drives as a secondary backup repository. They are formatted NTFS and are taking over a day to complete a file merge. I would like to format them using ReFS, but have read that USB drives are not supported. This comes from sites that are over 5 years old. So I was hoping someone where could let me know if ReFS is now supported on USB drives.

[HannesK]

Hello,
the two websites below should answer the question. The last issues happened in January 2022 and the Veeam forums have many posts around that.

https://docs.microsoft.com/en-us/window ... s-overview

All ReFS supported configurations must use Windows Server Catalog certified hardware and meet application requirements.

https://support.microsoft.com/en-us/top ... 9b0ee86c65

This issue may occur because the ReFS file system is not supported on removable media

Best regards,
Hannes

[Brad-Translucent]

Thanks for that.

[bbuchanan]

While ReFS on removable media is not supported, I do have a tertiary repository with weekly rotating USB drives, formatted with ReFS large blocks and after each rotation I do a test restore on the removed drive and it's always succeeded.

I'm not even doing a "safe" removal, just swapping the drive Monday morning. I did schedule the backup copy job to run at a specific time each evening and I was checking that the job wasn't running, but I don't even do that now. If I forget to swap the drive, or take Monday off, or a week, the merge does use fast block clone and doesn't take very long.

This USB drive is not my first backup, I also have SOBR Off-load, and it's not even my secondary DR site backup, and I always restore the last restore point onto an isolated system and I've been able to accept the risks.

To prepare each 16-TB USB drive I use diskpart, list disk, select disk, clean, convert gpt, create partition primary, format quick fs=refs unit=64k label="{DriveSerial}", assign letter=e

[HannesK]

Hello,
I know that it works (and many customers do it, as shown in other discussions on the forums). I do backups to REFS with USB drive with my Veeam Agent for Windows since years.

That does not change the fact, that it's unsupported. While it's okay to run unsupported for my laptop, I cannot recommend it to anyone in production.

Best regards,
Hannes

[Andreas Neufert]

The main topic why it is unsupported is the automatic ReFS version change. There are many healing and auto update/repair things happening in the background.
Whenever you connect the volume to a newer Windows version/update, potentially changes are automatically applied that makes it uncompatible or broken on the previous windows version.

Example you backup with the server, connect the USB later to your Windows Client and then back to the server and the server can not read anymore the data or potentially even harm them as it does not understand the correct format.

[Gustav]

In my experience, ReFS works well with USB drives.
But, after a server upgrade to, say, 2022, do clean and reformat the drives (see DiskPart steps above listed above post457987.html#p457987 by @bbuchanan.

[WAG357]

I am using 12TB USB ReFS formatted drives on Windows Server 2022 for Backup Copy jobs and they are working well.
I rotate them monthly and I do reformat each time a drive comes up for re-use and so far so good.
Just wanted to give my experiences on this.