Recovering from a disk failure without a hot spare disk

About this section

How disk failures affect the NetCache appliance depends on whether a hot spare disk is installed. This section describes how the NetCache appliance reacts to a disk failure when a hot spare disk is not available.

What happens with a single disk failure

For all models except the C1100, C1105, and single-disk C1200, if a single disk fails and a hot spare disk is not installed, the appliance continues to run without losing any data, but with a degraded performance.

The C1100, C1105, and single-disk C1200 models enter a system panic when a single disk failure occurs. The appliance must be halted and powered down before having the disk removed and replaced. Additionally, for the C1200 model, see What happens with cold swap devices.

The disk failure causes automatic shutdown after 120 hours. You can restart the appliance without fixing the disk, but the appliance continues to shut itself off every 120 hours until you repair or replace the disk.

The appliance sends a warning message to the Messages log and the system console every hour after a disk has failed.

Caution
Replace the disk as soon as possible because a second disk failure can cause the NetCache appliance to lose the entire file system.

What happens with a double disk failure

If a second disk fails while the NetCache appliance is operating in degraded mode, or if two disks fail at the same time, the file system is damaged and cannot be repaired. You must reinstall both the file system and the NetCache software in that case. See the topics on backing up and restoring a system configuration file in the Appliance Manager online Help for more information.

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.

What happens after you replace a disk drive

After you replace a disk drive, when the NetCache appliance boots, it detects the new drive, starts file service, and rebuilds the missing data in the background with minimum interruption to service. For a single-disk C1200 model, you must reinstall the NetCache appliance software and licenses after replacing a disk drive.

What happens with cold swap devices

The C1200 appliance disk drives are cold swap drives, which means the appliance must be halted and powered off before you remove or install a drive. The C1200 uses a compact flash PC-card as its primary boot device (default). The PC-card resides on the C1200 and is normally never removed.