HP P9000 Provisioning for Mainframe Systems User Guide (AV400-96369, October 2011)

For example, when the system disk is used as an audit log buffer, you set parameters to enable
the audit log buffer. The Audit Log feature recognizes the LDEV number of the system disk and then
accesses it as a buffer. The system disk must have sufficient capacity to accommodate the audit
log buffer. See Hitachi Audit Log User Guide for more information about how to enable the audit
log buffer.
To designate the system disk as the buffer area for audit logs, do one of the following:
• In the Audit Log Setting window, set Audit Log Buffer to Enable.
• Set system option mode (SOM) 676 to ON.
You can create a system disk on either a mainframe or an open system. To create a system disk,
you create an LDEV and then designate it as a system disk in the Create LDEVs wizard (see
(page 33)). The system disk designation prevents other storage system structures from accessing
it. It is not available to hosts, or a command device, pool volume, journal, and so on. The system
disk is part of one parity group. When an LDEV is defined as a system disk, the LDEV cannot be
allocated to a port.
The buffering area capacity for the audit log buffer is: 185 cylinders if the track format is 3380-3,
6586, or NF80; or 154 cylinders if the track format is 3390 or 6588. Therefore, before using the
audit log, make sure to prepare the system disk to have at minimum the above mentioned free
capacity in the volume. The size of the system disk could be 1 GB if you want some spare capacity,
or as large as 15 GB to accommodate the amount of system information that could be stored on
it.
If you find you do not need a system disk, you can delete the system disk and convert the volume
to free space (see (page 38)).
System disk rules, restrictions, and guidelines
Rules
• The minimum size of the system disk should be 130 MB in order to accommodate audit log
buffer information.
• When creating the system disk in the mainframe volumes, assign the LDKC:CU:LDEV number
that is not defined to the host's I/O generation.
• The LDKC:CU:LDEV number assigned to the system disk should be distinguishable from the
one for a normal volume.
• Use the Delete LDEVs function to delete the system disk.
Restrictions
• The system disk cannot be created on a V-VOL.
• The system disk can be specified as any emulation type except 3390-V.
The system disk cannot be created on an LDEV whose emulation type is 3390-V.
• A system disk cannot be used for any other function or connected to a port.
• Normal data must not be stored in the system disk.
• The bind mode of Cache Residency must not be set to the system disk.
• You cannot define a SCSI path for a system disk. Therefore, you cannot issue I/O from an
open or a mainframe system host. The device number is still seen by the mainframe volume,
but the device response is not operational. If you issue I/O from a mainframe system host, a
failure is reported as a CC=3 condition.
• The system disk should not be deleted or blocked while it is being used. Delete or block the
system disk when it is not being used.
44 Configuring custom-sized provisioning