Ignite-UX and SAS white paper

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Release C.7.10 of Ignite-UX improved recovery by preserving hardware paths and legacy device
file names under the sasd driver if hardware paths are available for swapping at installation time.
As a result, you do not have to import LVM data volumes manually.
SAS RAID LUNs
You should be aware of the following information when you configure RAID LUNs.
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Ignite-UX fully supports a configuration where only RAID LUNs are presented to a system. (This
includes having a hot spare configured.) Note that the HP PCI/PCI-X SAS MPT Adapter supports a
maximum of two RAID LUNs and a hot spare. SAS RAID LUNs must be configured from EFI before
installing HP-UX. Please consult the hardware documentation of your system and Core I/O card for
information on how to configure a SAS RAID LUN.
Important:
After initial system configuration you cannot add or remove SAS RAID
LUNs. Creating or deleting SAS RAID LUNs post-installation may cause
the hardware paths of SAS RAID LUNs to change during a cold-install or
recovery session.
If you have a system containing a mixture of RAID LUNs and individual SAS devices, the devices
used for the RAID LUNs and the global spare should be configured from Bay 8 working
downwards, and the individual SAS drives populated from Bay 1 upwards. Do not change the
configuration after system installation; until agile recovery is implemented, you risk encountering the
recovery issues discussed elsewhere in this white paper.
Recovery and cold installation
For Ignite-UX releases prior to C.7.5, use the hardware path of a device as the unique identifier for
a device. As mentioned above, if you change your SAS configuration, the hardware path for SAS
devices on HP-UX 11i v2 and for legacy DSFs on HP-UX 11i v3 can change when you reinstall or
recover a system. This effectively breaks Ignite-UX’s ability to automatically use the correct devices
when the SAS configuration changes. However, only some changes break the association of
hardware path to SAS device.
The following configuration changes
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might cause the hardware path associated with a SAS device
to change if the system is reinstalled or recovered:
- Placing a SAS device into an empty lower Bay
- Creating a SAS RAID device post-installation
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The restrictions discussed by this white paper regarding individual SAS devices do not apply to the P400 Core I/O card. The P400 Core
I/O card presents only RAID LUNs to the system; it is not possible to present individual SAS drives to a system.
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It is important to understand that making these changes at any time – while a system is running, or down, or recovering, will cause the issues
discussed here about hardware path changes.