HP StorageWorks 2000 Modular Smart Array Reference Guide (481599-003, August 2008)

Chapter 7 Troubleshooting Using SMU 203
Reconstructing a Virtual Disk
If one or more drives fail in a redundant virtual disk (RAID 1, 3, 5, 6, 10, or 50) and
properly sized spares are available, the storage system automatically uses the spares
to reconstruct the virtual disk. Virtual disk reconstruction does not require I/O to be
quiesced, so the virtual disk can continue to be used while the Reconstruct utility
runs.
A properly sized spare is one whose capacity is equal to or greater than the smallest
drive in the virtual disk. If no properly sized spares are available, reconstruction
does not start automatically. To start reconstruction manually, replace each failed
drive and then do one of the following:
■ Add each new drive as a vdisk spare (Manage > Virtual Disk Config > Vdisk
Configuration > Add Vdisk Spares) or a global spare (Manage > Virtual Disk
Config > Global Spare Menu > Add Global Spares). Remember that a global
spare might be taken by a different critical virtual disk than the one you intended.
■ Enable the Dynamic Spare Configuration option on the Manage > General Config
> System Configuration page to use the new drives without designating them as
spares.
Reconstructing a RAID-6 virtual disk to a fault-tolerant state requires two properly
sized spares to be available.
■ If two drives fail and only one properly sized spare is available, an event
indicates that reconstruction is about to start. The Reconstruct utility starts to run,
using the spare, but its progress remains at 0% until a second properly sized spare
is available.
■ If a drive fails during online initialization, the initialization fails. In order to
generate the two sets of parity that RAID 6 requires, the RAID controller fails a
second drive in the virtual disk, which changes the virtual disk status to Critical,
and then assigns that disk as a spare for the virtual disk. The Reconstruct utility
starts to run, using the spare, but its progress remains at 0% until a second
properly sized spare is available.
The second available spare can be an existing global spare, another existing spare
for the virtual disk, or a replacement drive that you designate as a spare or that is
automatically taken when dynamic sparing is enabled.
During reconstruction, though the critical virtual disk icon is displayed, you can
continue to use the virtual disk. When a global spare replaces a drive in a virtual
disk, the global spare’s icon in the enclosure view changes to match the other drives
in that virtual disk.