Changing the Read/Write State of an Online Logical Unit
Issue
- Certain storage devices provide the user with the ability to change the state of the device from Read/Write (R/W) to Read-Only (RO), and from RO to R/W. This is typically done through a management interface on the storage device. When the change is made, the operating system does not automatically update its view of the state of the device. As a result, any command that attempts to write to the device fails, even though the state of the device was changed to Read/Write at the storage server.
- For example, when trying to extend any existing volume group on the server, the
vgextendcommand fails as follows:
vgextend /dev/test_vg /dev/mapper/SEMC_SYMMETRIX_104955328000
/dev/mapper/SEMC_SYMMETRIX_1049554C8000: write failed after 0 of 8192 at 24576: Operation not permitted
Environment
- Red Hat Enterprise Linux 5, 6
- Storage stack
- LVM --> device mapper multipath --> SCSI --> EMC Symmetrix (or other storage device that allows the manager to change the Read/Write state of the logical unit.
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