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Writing the System Dump File to the System Disk  



If you have more than one path to the system disk, or the system disk is a shadow set with multiple members, you must take additional steps to ensure that a system dump can be written to the system disk.

System Dump to System Disk on Alpha and I64 Systems  

If there is more than one path to the system disk, the console environment variable DUMP_DEV must describe all paths to the system disk. This ensures that if the original boot path becomes unavailable because of failover, the system can still locate the system disk and write the system dump to it.

If the system disk shadow set has multiple members, the console environment variable DUMP_DEV must describe all paths to all members of the shadow set. This ensures that if the master member changes, the system can still locate the master member and write the system dump to it.

If you do not define DUMP_DEV, the system can write a system dump only to the physical disk used at boot time using only the same physical path used at boot time. For instructions on setting DUMP_DEV, see DOSD Requirements on Alpha and I64 Systems.

You can write the system dump file to an alternate disk (see DOSD Requirements on Alpha and I64 Systems), but when you do so, you must still define a path to the system disk for writing error logs. Therefore, DUMP_DEV must contain all paths to the system disk in addition to the paths to the alternate dump disk.

On Alpha systems, certain configurations (for example, those using Fibre Channel disks) may contain more combinations of paths to the system disk than can be listed in DUMP_DEV. In that case, HP recommends that you include in DUMP_DEV all paths to what is usually the master member of the shadow set, because shadow set membership changes occur less often than path changes.

Also on Alpha systems, if there are more paths than DUMP_DEV can contain, HP recommends that you define all paths to the dump disk and as many paths as possible (but at least one) to the system disk. Note that the system disk paths must come last in the list.


NoteThe error log dump file is always created on the system disk so that error log buffers can be restored when the system is rebooted. This file is not affected by setting the DUMPSTYLE system parameter or the DUMP_DEV environmental variable.

The system chooses the first valid device that it finds in the list as the dump device. Therefore, the dump disk path entries must appear before the system disk entries in the list.

On Alpha systems, the number of devices that can be included in DUMP_DEV is limited. This limit varies from platform to platform, and it also depends on the device configuration. Some platforms allow only a single device; others allow a list. Systems that allow a list of devices limit the length of the list to 256 bytes in the internal format that the console subsystem uses. This length provides space for 4 entries if SCSI or CI-based disks are used, and 8 to 9 entries if fibre-channel disks are used.

On I64 systems, up to 99 devices can be included in DUMP_DEV, regardless of platform or device configuration.


See "Designating the Dump Device on I64 Systems" on page 80 for more information.

Use either of the following methods on I64 systems:

System Dump to System Disk on VAX Systems  

To ensure that the system can locate the system disk and write the system dump to it when there is more than one path to the system disk, or when the system disk shadow set has multiple members, you must follow the platform-specific instructions regarding booting. On some VAX systems, you must set appropriate register values; on other VAX systems, you must set specific environment variables. See the upgrade and installation supplement for your VAX system for details.

Note that if the system has multiple CI star couplers, the shadow set members must all be connected through the same star coupler.


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