About adding and removing disks

Why you might add or remove disks

You might want to add disks to the appliance to increase available disk space, to add a hot spare, or to replace a failed disk. You might want to remove a disk from your appliance because you want to use it in another appliance, because it has failed, or because it is producing excessive error messages.

Note
The NetCache C1100 and C1105 appliances have no replaceable components. If a disk fails or produces an excessive amount of errors, the entire system must be replaced.

New and previously used disks

In most cases, the disk you add will be a new disk; that is, the disk has never been used.

If the disk you want to add to the appliance was previously used by another NetCache appliance or a Network Appliance filer, make sure that you unfail the disk before you begin. See the details in the Appliance Manager online Help.

Platforms with an internal disk tray

If you are using a appliance model with an internal tray, the number of disks you can add depends on the model you purchased. You cannot add more disks than the internal trays the appliance was shipped with can accommodate. See Platform support of RAID and internal disk trays for a list of platforms with internal disk trays.

Because the disks are internal, you cannot replace a failed disk while the system is in operation. You must shut down the system first to replace a failed disk in a system with an internal disk tray.

When to add or remove disks in external disk platforms

The Appliance Manager enables you to add or remove a single disk from the system without interrupting appliance service to your users. However, during the procedure, the appliance operates in proxy-only mode. That is, the appliance proxies Web requests on behalf of users by retrieving the objects from the source Web server. No new objects are saved to the cache, and no objects in the cache are served to users. Because users might notice slower Web performance during this time, it is a good idea to plan to add or remove disks when you expect the load on the appliance to be light.

If you are adding more than one disk or a new disk shelf to your system

If you are adding several disks or a new disk shelf to your system, the process might be faster if you shut down the system. If you shut down the system, you can add all the disks at once, then reboot the system. Otherwise, you must add the disks one at a time using the Appliance Manager, as explained in the Appliance Manager online Help.

If you must remove more than one disk from your system

If you must remove more than one disk from the appliance, Network Appliance recommends that you remove and replace each disk one at a time You must allow the data to fully reconstruct on the new disk beforeyou remove another disk.

Caution
Removing more than one disk at a time from your appliance will result in data loss. If you remove more than one disk at a time from the appliance, the appliance will not be able to rebuild the data from the remaining disks. You must reinstall both the file system and the NetCache software and licenses in that case.

If you are performing disk operations online

If you are performing disk operations online, you can perform only one operation at a time. The appliance does not allow you to begin a new disk operation if a previous disk operation is incomplete.

Using hot spares in external disk platforms

If you want to prevent loss of service time, you can add one or more hot spare disks. When a data disk on the appliance fails, a hot spare automatically replaces it without a system shutdown.

To determine whether your appliance contains a hot spare, see the Disk - Management page (Maintenance tab > Disk > Management) of the Appliance Manager. This page lists all the disks of the appliance and indicates whether a disk is a parity, data, or spare disk.

You can add more hot spare disks to the system at any time, as long as disk slots are available. However, you need to follow the procedure described in the Appliance Manager online Help.

About adding disks to your system

When you add a single disk to the appliance, the disk is initially recognized as a hot spare. If you want the disk to be used as a data disk, you must "promote" the hot spare disk to a data disk.

Procedures for installing and promoting disks are provided in the Appliance Manager online Help.

About removing disks from your system

You can remove one disk from the appliance and still have access to all data stored on that disk. However, do not remove more than one disk at a time from the appliance.

See the procedures in the Appliance Manager online Help.

About replacing a failed disk on your system

The procedure for replacing a failed disk differs slightly, depending on whether a hot spare is installed in the appliance. If a hot spare is installed, the appliance promotes the hot spare to a data disk and reconstructs the data from the failed disk. However, if no hot spare is available, the appliance operates in a degraded mode until you replace the failed disk.

See the Appliance Manager online Help for detailed procedures about replacing failed disks and possible errors during disk replacement.

Note
The procedures for replacing a disk apply to appliances with external disk tray systems (the disks are exposed and easily accessible). The procedures do not apply to internal disk tray systems, where the disks are not easily accessed. See Platform support of RAID and internal disk trays for more information.