HP A3550A - High Availability Disk Arrays Model 20 Storage Enclosure User Manual page 106

Table 2-3 High Availability Topology Error Recovery
Failing Continue
component after failure?
Disk module Yes
SP No on path to
failed SP;
Yes on alternate
path through
second SP
Fan pack Yes
Power supply Yes if three
unit power supply
units (required
for high
availability);
No if two power
supply units (no
high availability)
HP FC-AL No on path to
Hub failed hub;
Yes on alternate
path to other
hub
FC I/O No on path to
adapter failed adapter;
Yes if array has
dual SPs and
alternate paths
have been
configured
FC cable No on path to
failed cable;
Yes if array has
dual SPs and
alternate paths
have been
configured
2-14 High Availability Topology
What happens and how to recover
Applications continue to run on all supported RAID levels (RAID-1, 1/0,
3, and 5). The system administrator or service provider hot-replaces
the failed disk module.
Ownership of the failed SP's LUNs can transfer automatically to the
remaining operational SP if primary and alternate paths have been
configured in LVM. If so, LVM switches automatically and transparently
to the alternate path. The system administrator or service provider hot-
replaces the failed SP.
Applications continue to run. The system administrator or service
provider hot-replaces the fan pack.
If all three power supply units required for high availability are present,
applications continue to run when one power supply unit fails. The
system administrator or service provider hot-replaces the failed power
supply unit.
If two power supply units are present the disk array fails. The system
administrator or service provider replaces the failed power supply unit
and the system administrator restarts the operating system and
applications.
I/O operations fail along the path to the failed HP FC-AL Hub. I/O
operations can transfer automatically to the other HP FC-AL Hub if
primary and alternate paths have been configured in LVM. If so, LVM
switches automatically and transparently to the alternate path. The
authorized service provider hot-replaces the failed HP FC-AL Hub.
I/O operations fail along the path through the failed adapter. If the host
has two FC adapters connected to a dual-SP disk array, the array can
be accessed through the path to the operational adapter and SP if
primary and alternate paths have been configured in LVM. If so, LVM
switches automatically and transparently to the alternate path. The
authorized service provider replaces the failed adapter and the system
administrator restarts the operating system and applications.
I/O operations fail along the path through the failed cable. If the host
has two FC adapters connected to a dual-SP disk array, the array can
be accessed through the operational path if primary and alternate paths
have been configured in LVM. If so, LVM switches automatically and
transparently to the alternate path. The authorized service provider hot-
replaces the failed cable.