General Considerations and Limitations

This section describes known limitations.

This section covers the following topics:

• Disks became unresponsive after plugging back in
• Unexpected I/O interruptions when creating more virtual devices
• AutoSupport notification might fail during NearStore VTL startup
• Restored tape devices are not recognized by a backup program
• There is no notification from VTL when no writable disk space is available

Disks became unresponsive after plugging back in

After unplugging and plugging in the disks, the disks became unresponsive. You might also observe many "I/O not completing" messages on the console.

Versions of disk shelf firmware prior to AT-FCX ver 3.2 contain a bug that causes this problem. Although the bug is present in 300-GB drives, it is only triggered with 500-GB drives. You can prevent the problem by upgrading the disk shelf firmware on your NearStore VTL appliances. The NearStore VTL software version 4.1.2 package includes updated shelf firmware that you can install (see New and changed features).

Unexpected I/O interruptions when creating more virtual devices

I/O might get interrupted from the virtual drives while adding a new virtual library or expanding an existing library. This is because the VTL sends out UNIT ATTENTION on all the LUNs to inform the initiator that the REPORT LUNS data has changed.

AutoSupport notification might fail during NearStore VTL startup

While a NearStore VTL appliance is starting up, conditions might occur that trigger an AutoSupport notification email, but if the network is not yet initialized, the attempt will fail. In such a case, the usual event action logging will occur on the appliance, but NetApp support will not receive notification.

Restored tape devices are not recognized by a backup program

After recovering a VTL configuration from a saved configuration file, the restored devices might not be recognized by the backup application. The restored devices have new serial numbers and so are not registered with the backup application. Rerun the storage device wizard to add the new devices.

There is no notification from VTL when no writable disk space is available

If a RAID group is degraded, and all the other RAID groups are full, a write will fail. Note that although a warning is issued when a RAID group becomes degraded, because there is still free space in the degraded RAID group (although it is not writable), no error is issued when there are no available writable disks in the storage pool.