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teaton-0636 avatar image
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teaton-0636 asked SadiqhAhmed-MSFT edited

MARS Backup with iSCSI Volume formatted as ReFS - not compatible?

I have the MARS backup agent installed on a Win 2019 server with an iSCSI volume mounted formatted as ReFS.

It appears I cannot add folders/files from this volume as it doesn't appear in the list of selectable volumes, I've checked the MARS compatibility matrix but doesnt state anything about iSCSI and/or ReFS not being supported?

Anyone else had the same problem and if so is there a workaround?

azure-backup
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1 Answer

SadiqhAhmed-MSFT avatar image
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SadiqhAhmed-MSFT answered SadiqhAhmed-MSFT edited

@teaton-0636 Thank you for your post and I apologize for the delayed response!

Please check the following: Support matrix for the MARS agent - Azure Backup | Microsoft Docs


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I believe reasoning for why only NTFS is supported is:

The NTFS file system maintains an update sequence number (USN) change journal. When any change is made to a file or directory in a volume, the USN change journal for that volume is updated with a description of the change and the name of the file or directory. As files, directories, and other NTFS file system objects are added, deleted, and modified, the NTFS file system enters change journal records in streams, one for each volume on the computer. Each record indicates the type of change and the object changed. The offset from the beginning of the stream for a particular record is called the update sequence number (USN) for the particular record. New records are appended to the end of the stream.

MARS agent uses the USN to track the changes. This method is pretty fast as we are only pulling the files that changed since the last backup.



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