A virtual disk can be online or offline. In the online state, the virtual disk is active and all data is accessible.
If a failure occurs, appropriate console warning messages and status information will be displayed. If a single drive fails on a RAID array (levels 1, 4 and 5), the virtual disk will remain online and all data will be accessible; in other circumstances, the virtual disk may go offline. Simple, concatenated and stripe virtual disk types always remain online as disk errors are passed back to the application.
Status information is displayed in the Virtual Disk Manager after the disk or piece information. Possible error states are:
The Virtual Disk Manager uses timestamps on RAID virtual disk configurations to ensure proper operation and data integrity. If a timestamp on one of the mirror virtual disk pieces becomes invalid, the piece will not be fully configured. You cannot set the timestamps to a known state on a mirror virtual disk that is online.
If this happens, the out-of-service piece on the mirror root device cannot be restored.
If the primary disk fails during the system reboot (when
mirroring the root disk for the first time), the
array will go offline and the system boot will fail. At
this point in the boot sequence, the system cannot switch
over to the secondary disk if it has not been completely
restored. Before replacing the primary drive or rebuilding
the system, remove power from the secondary disk and try to
boot the system. If the primary disk is not completely bad,
the system will boot. When the system boots,
unmirror the root device.
Once the problem has been corrected, try to mirror the root
When an array or mirrored virtual disk has a mounted filesystem and the array or mirror goes offline due to error conditions, the filesystem becomes unusable. At this point, the filesystem cannot be unmounted (much the same as a hard disk failure). The system must be rebooted to clear this condition.
An array or mirror may go offline when more than one piece is out of service or one piece is out of service and parity is out of date. To rectify this:
When the system has many RAID virtual disk configurations, with large cluster sizes or a heavy I/O load, the performance of the array may be reduced due to the high contention for system resources (buffers, kernel virtual memory, and so on). By increasing the total amount of physical memory, the system and array performance can be improved. See ``Warning messages'' for more information on driver error messages related to kernel virtual memory.