Please follow the next steps to clear the read-only mode
1. Open Command Prompt
2. Run diskpart
3. List and select the SAN shared disk
4. Type attribute disk clear readonly

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C:\Users\Administrator>diskpart

Microsoft DiskPart version 6.0.6002
Copyright (C) 1999-2007 Microsoft Corporation.
On computer: COMPUTERNAME

DISKPART> list disk

 Disk ###  Status      Size     Free     Dyn  Gpt
 --------  ----------  -------  -------  ---  ---
 Disk 0    Online        64 GB      0 B
 Disk 1    Offline       78 GB  2048 KB   <--- The share disk is usually reported as Offline

DISKPART> select disk 1

Disk 1 is now the selected disk.

DISKPART> detail disk

ROCKET IMAGEFILE SCSI Disk Device
Disk ID: 02872505
Type   : iSCSI
Bus    : 0
Target : 0
LUN ID : 0
Read-only  : Yes   <--- Make sure of read-only mode
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No

There are no volumes.

DISKPART> attribute disk clear readonly

Disk attributes cleared successfully.

DISKPART> detail disk

ROCKET IMAGEFILE SCSI Disk Device
Disk ID: 02872505
Type   : iSCSI
Bus    : 0
Target : 0
LUN ID : 0
Read-only  : No  <--- Make sure of that read-only mode has been cleared
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No

There are no volumes.
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