Setup guide

5-6
Cisco 6400 Software Setup Guide
OL-1183-04
Chapter5 Redundancy and SONET APS Configuration
NSP Redundancy
Disk mirroring provides full NSP redundancy for the NRP-2, which depends on the NSP for image and
file storage. Without disk mirroring, there is no guarantee of NRP-2 support after an NSP failover (user
intervention might be required to restore the NRP2 state to that prior to the failover). With disk mirroring
enabled, NRP-2 has continued support from the NSP, except during the relatively short NSP failover
period.
When PCMCIA disk mirroring is enabled, as it is by default, disk synchronization is initiated each time
that:
• The primary or secondary NSP boots or reloads
• The secondary NSP is inserted into the Cisco 6400 chassis
• A PCMCIA disk is inserted into disk slot 0 of the primary or secondary NSP
• The PCMCIA disk in disk slot 0 of either NSP is formatted
• A command is entered to:
– Re-enable disk mirroring (mirror)
– Explicitly initiate disk synchronization (redundancy sync)
– Modify or reorganize the files on the disks (copy, rename, delete, mkdir, format)
Note PCMCIA disk mirroring is not supported in Cisco IOS Release 12.1(4)DB and earlier releases. Use the
dir, mkdir, and copy EXEC commands to manually copy files from the primary NSP’s PCMCIA disks
to the secondary NSP’s PCMCIA disks.
PCMCIA disk mirroring also introduced new labels for pairs of mirrored disks:
• mir-disk0—PCMCIA disks in disk slot 0 of both NSPs
• mir-disk1—PCMCIA disks in disk slot 1 of both NSPs
The mir-disk0 and mir-disk1 labels enable you to perform any integrated file system (IFS) operation
(such as copy, rename, and delete) on the same file on both the primary and secondary disks.
Restrictions and Recommendations
• If an NSP failover occurs during disk synchronization, the file that is being copied is deleted from
the receiving disk, instead of only partially copied. This means that the file is no longer available to
the NRP-2. The amount of time it takes to complete disk synchronization varies for each system, but
depends on the number and sizes of files being copied.
• Disk mirroring (automatic data synchronization between a pair of disks) is not supported between:
– Two disks on a single NSP
– Two disks with mismatched slot numbers (disk0: and disk1:)
You can, however, initiate disk synchronization between disk0: and disk1: on the active NSP, even
in a single-NSP system.
• Cisco recommends that you use PCMCIA disks of the same memory capacity.