Disk failure with a hot spare disk

About this section

This section describes how the filer reacts to a single or double disk failure when a hot spare disk is available.

Filer replaces disk with spare and reconstructs data

If a disk fails, the filer

Replaces the failed disk with a hot spare disk (if RAID DP is enabled and double disk failure occurs in the RAID group, the filer replaces each failed disk with a separate spare disk). Data ONTAP first attempts to use a hot spare disk of the same size as the failed disk. If no disk of the same size is available, Data ONTAP replaces the failed disk with a spare disk of the next available size up.
Reconstructs in the background the missing data onto the hot spare disk or disks
Logs the activity in the /etc/messages file on the root volume
Sends an Autosupport message
Note
If RAID DP is enabled, the above processes can be carried out even in the event of simultaneous failure on two disks in a RAID group.

During reconstruction, file service can slow down.

Caution
After the filer is finished reconstructing data, replace the failed disk or disks with new hot spare disks as soon as possible so that hot spare disks are always available in the system. For information about replacing a disk, see Chapter 5, Disk Management.

If a disk fails and no hot spare disk is available, contact Network Appliance Technical Support.

Network Appliance recommends keeping at least one matching hot spare disk for each disk size and disk type installed in your filer. This allows the filer to use a disk of the same size and type as a failed disk when reconstructing a failed disk. If a disk fails and a hot spare disk of the same size is not available, the filer uses a spare disk of the next available size up.

Information

In addition to disk failure and hot spare disk replacement, the /etc/messages file on the root volume logs any failure in a periodic check of the hot spare disk. For more information, see the na_sysconfig(1) and na_messages(5) man pages.