SCF Reference Manual for the Storage Subsystem (G06.24+, H06.03+)

Configuring Magnetic Disks

SCF Reference Manual for the Storage Subsystem—529937-007

6-12

Mirrored Disk Placement

Mirroring Without NonStop S-Series Enclosure Interleaving

For proper fault tolerance, always install the two disks of a mirrored volume on different

SCSI buses:

•

For internal disks in a NonStop S-series system enclosure, if you install the primary

disk in an odd-numbered slot, install the mirror disk in an even-numbered slot.

•

For model 45xx disks, configure the primary disk and mirror disk of a mirrored

volume in different disk modules.

Mirroring With NonStop S-Series Enclosure Interleaving

Enclosure interleaving improves the fault tolerance of your NonStop S-series system

by allowing you to install the disks of a mirrored volume (or configure the adapters for

the two disks of a mirrored volume) in separate enclosures within the same topology

branch. Configuring paths across multiple enclosures increases availability, because

no enclosure is a single point of failure preventing access to the storage device.

•

For internal disks, install the halves of a mirrored volume in separate enclosures.

The disks that make up a mirrored volume need not be in an even-numbered and

odd-numbered slot. The -P and -B paths must be in one enclosure. The -M and

-MB paths are in another enclosure in the same topology branch.

•

For model 45xx disks, install their adapters in separate enclosures.

For more information about enclosure interleaving, see to the NonStop S-Series

Planning and Configuration Guide.

Mirroring With M8xxx Fibre Channel Disks

For model M8xxx disks, configure the primary disk and mirror disk of a mirrored

volume in different disk-drive enclosures, connected to a different pair of Fibre Channel

loops.

If disk-drive enclosures are daisy-chained, the primary disk and mirror disk of a

mirrored volume must be in different sets of daisy-chained enclosures.

Note. Enclosure interleaving does not apply to Integrity NonStop NS-series systems.