Removing a Unit

Removing a unit allows you to safely remove drives from a controller in order to move the unit to another controller or to store the drives for safekeeping purposes. This process is sometimes referred to as "array roaming." Hot swap carriers are required unless you power down first.

When you remove a unit (in contrast to deleting a unit), information about the unit remains intact on the drives. This allows the drives to be reassembled into a unit again on this controller, or if moved to another controller.

Warning: It is important to remove the unit through software, before removing it physically. Failure to do so could result in a system crash or hang and may even corrupt the data and the unit configuration from being reassembled later.

Note: You can also remove a drive, if you want to force a degrade on a redundant unit, or if you want to remove a drive from the "Available Drives" list so that you can then remove it from the system. For more information, see Removing a Drive.

To remove a unit

Note: If you do not have hot swap carriers, you do not need to remove a unit via 3DM. Simply power down the system and remove the applicable drives. Refer to your system's user guide for details on removing fixed disks. If you do have hot swap carriers, follow the steps below.

Make sure no I/Os are being issued to the unit you want to remove.

For example, make sure you are not copying files to the unit, and make sure that there are no applications with open files on that unit.

Unmount the unit.

This step is very important. If a unit is not unmounted and you remove it, it is the equivalent of physically yanking a hard drive out from under the operating system. Resulting behavior depends on which operating system you are using and what kind of I/O is being done, however you will typically see really bad results, bad errors, and most likely a reset of the controller or a system hang.

Under Windows, go to Start > Administrative Tools > Computer Management, and select Disk Management. Remove the logical drive letter for the unit.

Under Linux and FreeBSD, you can unmount the unit with this command:

umount <mount location> 

In 3DM, choose Management > Maintenance.
In the Unit Maintenance table on the Maintenance Page, select the unit you want to remove and click Remove Unit.
When a message asks you to confirm, click OK.

The unit number and information is removed from the Maintenance page in 3DM.

The operating system is notified that the unit was removed. In Linux the device node associated with this unit is removed. In Windows the Device Manager will reflect the changes under the disk drives icon.

You can now physically remove the drives and move them to another controller. If you have a hotswap carrier, you can do this without shutting down the system. If you do not have a hot-swap carrier, power-down the system and ground yourself before making changes to the hardware.

If you change your mind and want to reuse the drives and unit on the current controller, click Rescan Controller.

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