Error Code 21 - The device is not ready from Macrium backup

Hi
During macrium online backup I am getting error “Backup aborted! - Unable to read from disk - Error Code 21 - The device is not ready”.
Macrium says that they are getting “Error Code 21 - The device is not ready” from windows.
I have checked thread Backup aborted! - Unable to read from disk - Error Code 21 - The device is not ready.
However I did not find a hint for my case in said thread.

Customer set up:
1. Windows 10 latest version at Lenovo desktop.
2. Disks: Samsung 870 SATA SSD for system disk and internal SATA HDD for backup.
3. No USBs connected, only above two SATA disks.
4. Macrium home 8 latest version , full backup every Tuesday, incremental every Thursday

In this setup customer is intermittently observing this error – 3 times within last 4 months.
I dialed in to customer 17.11, updated to latest version of macrium and ran incremental backup without issue.
But again today 28.11 issue occurred during full backup.
I doubt there are issues with this Samsung SSD from July 2022, but I have not yet run chkdsk c: \f or chkdsk c: \r \f.
So far I have only observed this issue at this customer desktop, not at any other customer.
Any suggestions?



Update 240118 with WA:
Even though I still do not know the root cause for this issue, it seems that rescheduling online backup to a less busy timeslot can be used as a WA. This is in line with this article from MSP360.
So in this case issue is not related to the disk, which has passed all the tests proposed.
If/when I get an update from Macrium R&D I will update this thread.

Hi, a thought.. this appears to be a business use case. As such I my first thought was to assume you're using a licensed version of Macrium, and so have access to Macrium's own forum.

As a minimum you can, of course, search their forum...

However I note this text in their license info:

You must only use a Macrium Reflect® purchased license for your own benefit and not to provide services for or on behalf of any other person including on a "service bureau" basis.

End User License Agreement - Macrium Software


I've not gone thru the detail but there is a technician's license- maybe that's appropriate.
Macrium Technicians License

Thanks- thought it better to check.

Have you run a check on the disk in question? Hard Disk Sentinel provides easy access to the disk's record of communication failures.

Simply run HDS and look at the GUI- bear in mind the count is historic.

You could also try creating the backup booting from MRs PE disk, rather than running MR within Windows. You say no USB's are connected.

Note that this idea succeeded in the case you quoted:
Backup aborted! - Unable to read from disk - Error Code 21 - The device is not ready.

Does this help?
VSS error: VSS_E_SNAPSHOT_SET_IN_PROGRESS - KnowledgeBase - Macrium Reflect Knowledgebase
This indicates a software conflict because some other program is also using VSS at the time and this would not be a problem using the Rescue Media. Have you changed/added some program that might interfere?

Further possible interpretations of error code 21:
Datto Windows Agent: Error Reading from Snapshot. Error: 21
Cause

Error: 21 is a Windows error code denoting that the specified device is not ready. Common causes are:

Disk errors
Filesystem errors
Insufficient free space on the affected disk of protected system
Insufficient available RAM on the protected system
Disk fragmentation on the affected disk of protected system
Excessive disk I/O (Possibly due to fragmentation)
Failed VSS transactions (Possibly due to the above problems)
Excessive amounts of data change since the initial snapshot of the volume

It's not something I've ever experienced on my 2 laptops...

You could try a clean boot, then see if that makes a difference..

Is there anything shown in the event viewer at the time this occurs?

The last section of my post suggests you should make sure that there's minimal disk activity whilst creating the image. (Sure you can normally use the PC whilst imaging is in progress...).

plaurits said:

During macrium online backup I am getting error “Backup aborted! - Unable to read from disk - Error Code 21 - The device is not ready”.....
....I doubt there are issues with this Samsung SSD from July 2022, but I have not yet run chkdsk c: \f or chkdsk c: \r \f.
So far I have only observed this issue at this customer desktop, not at any other customer.

An SSD of that age is almost certainly physically healthy, but there may well be logical corruption.

Chkdsk is almost certainly going to say C: is OK, but C: isn't the only partition being backed up. You need to check all the other partitions as well, one of the others is a likely suspect.

dalchina said:

It's not something I've ever experienced on my 2 laptops...

I've seen it once. If I remember correctly it was the System Reserved partition that was corrupt.

You can, of course, try imaging each separately as a test... thus the error will be specifically related to that partition.

Remember to try all of them, separately.