Hey Checkyourlogs Fans,

Today, I wanted to talk to you about an issue I had with one of my Rotation Media Veeam USB Backup Targets this week at a remote branch location. What we had to do this weekend was convert an older File Server that had pass-thru disks attached to ISCSI targets. This is not supported by traditional backup tools like Veeam Backup and Replication unless you use something like the Veeam Agent for Windows (VAW). So, we were following the process that I blogged about earlier: https://www.checkyourlogs.net/converting-virtual-machines-with-pass-through-disks-using-veeam-agent-for-windows-veeam-veeam/

During this process, we followed all the steps and ran the full backup job. The full backup pass took over 9 hours to complete, and when we went to extract the VHDx files from the backup, we encountered the following error message:

Failed to decompress LZ4 block: Incorrect decompression result or length (result: ‘1038202’, expected length: ‘1048576’. Failed to download disk. Agent failed to process method [DataTransfer.SyncDisk]. Exception from server: Shared memory connection was closed. Failed to upload disk.

I wasn’t sure if it was an issue with a bad CRC or defective USB HDD that we had attached at the remote branch location. We didn’t have an easy way to replace the drive, so I figured I would try taking the backup again and try exporting the disks again. To no avail, it failed again.

At this point, I decided to open up disk management, and I saw the drive was formatted out with the default exFAT file system. So, I wondered if re-formatting the drive as ReFS 64KB block size would make a difference, and you know what it did.

The export job ran for about 5 hours to complete, and we were able to complete the job of converting the file server as described in the article above

I hope this helps you out if you encounter this issue.