On a CRD disk (configuration disk) of a unit (MU, SU x86, HNC), the following data of the SE server configuration are stored:
General data of the SE server:
Model, name and location
Cross-unit data
Unit-specific data with contents that should remain available even after the unit fails or is powered off (not for HNC):
Model, SW version and host name
IP configuration
FC configuration
VM data for BS2000 (on SU x86 also for Linux and Windows)
Current configuration of the Net Unit switches
By default, the data are locally stored on an internally mirrored disk of the unit (MU, SU x86, HNC).
In addition to the internal configuration disk, up to two external CRD disks can be configured on external FC RAID systems, to which all MUs and SU x86 have access via a redundant connection.
This ensures consistency: Every MU and SU x86 reads the data of the SE server in the same way and the actions on these units can be coordinated.
The SE Manager displays information about the CRD disks, e.g. of an MU, in the Hardware -> Units -> [<se server> (SE<model>) ->] <unit> (MU) -> Information menu (see "Displaying CRD disks of the MU"):
Figure 5: MU with external CRD disks
External CRD disks are required in the following cases:
MU redundancy
Cluster
For the SE Cluster (Management Cluster), external CRD disks are sufficient on the MUs. For SU Clusters, external CRD disks are also required on SU x86.