My Disk is Read-only, Help!

Recently I helped someone on an issue where the customer had a disk that was part of a Windows 2008 R2 Service Pack 1 Cluster.  They could bring the disk online, but they couldn’t write to it.  During the course of troubleshooting, they ran Diskpart and looked at the attributes of the disk.  They found that the “Current Read-only State” attribute was set to Yes, but the “Read-only” attribute was set to No.  This seemed strange at first that they would not BOTH be set to Yes or both set to No.  They tried clearing the read-only attribute, but it would not set the “Current Read-only State” attribute to No even though the command did not return an error.

We found that the disk was set to read-only on the SAN and this was causing the problem.  When you see the “Current Read-only State” set to Yes, this is the true read-only status of the disk.  The “Read-only” setting just indicates if we as an OS have the disk set to read-only.

The following steps will show you how to use Diskpart to look at these settings and also how to clear them.

1.       Open a command prompt, type in Diskpart and then press Enter.

2.       Run the command “List Disk” and press Enter.


3.       Decide which disk you want to look at and then run the command “Select Disk n” where n stands for the number you see from the previous command.  In this case, I am going to look at disk 1.


4.       To see the attributes of Disk 1 now that it is selected, run the command “attributes disk”.


As you can see, I had already set the disk to Read-only, so both the “Current Read-only State” and “Read-only” attributes are set to Yes.

5.       To clear the “Read-only” attribute, run the command “attributes disk clear readonly”.


As you can see, now the “Current Read-only State” and “Read-only” attributes are set to No and the disk is now writeable.  To exit Diskpart, just type the word “exit” and then press enter.

Hopefully this will help you understand these attributes and help you diagnose a read-only problem with your disk.  Have a great day!

James Burrage
Senior Support Escalation Engineer
Microsoft Enterprise Platforms Support