I/O Chassis; Duration Of Dynamic Npartitions Operations; Sensitivity To Operating System Workload - HP Integrity rx7620 Configuration

I/O chassis

Many workloads are CPU-bound or memory-bound. When using cell online activation to increase the
capacity of a partition running such a workload, an I/O chassis does not need to be attached to the
cell.
In some cases, I/O resources can be considered private to an application and to the partition that
hosts it. An example would be a SCSI controller that connects to disks containing application data.
In such cases, it is not appropriate for the I/O resources to migrate to another partition along with a
floating cell.
The configuration guideline then is to configure the cellular complex so that private I/O resources are
attached to base cells. Floating cells used to satisfy demand for CPU and memory resources do not
need an I/O chassis attached. Any I/O attached to a floating cell must be shareable, such as
additional redundant connections to the network or to the storage fabric.

Duration of Dynamic nPartitions operations

The cell online activation operation must configure all resources on the new cell for use by the
operating system. It also rebalances some operating system parameters to suit the larger size of the
nPartition. For this reason, the operation can take some time to complete. The typical time to
complete cell online activation on a moderately loaded system is 60 seconds.
The cell online deactivation operation causes the operating system to discontinue use of all resources
on the cell to be deactivated. In particular, all data elements in memory must be preserved, either in
other memory or on disk. Some operating system parameters are rebalanced to suit the smaller size
of the nPartition. Therefore, the operation can take some time to complete. The typical time to
complete cell online deactivation on a moderately loaded system is 3 minutes.
If a Dynamic nPartitions operation is in progress, its status can be ascertained by the command
parolrad –m
If a Dynamic nPartitions operation is in progress and has not yet reached its commit point, it can be
canceled by the command
parolrad –c sequence_number
where sequence_number is the number returned by the invocation of the parolrad command that
initiated the Dynamic nPartitions operation. Most Dynamic nPartitions operations reach their commit
point within a few seconds and then can no longer be canceled.

Sensitivity to operating system workload

The duration of a Dynamic nPartitions operation is sensitive to the workload on the target partition. A
cell online activation operation is often used to increase the resources in a partition when it is
inadequate to meet the demands of the workload. Therefore, it is usual and expected to perform cell
online activation to a partition that is overutilized, and the duration of such an operation is not
expected to exceed 5 minutes.
By contrast, a cell online deactivation operation decreases the resources in a partition. So, it should
generally not be performed on a partition that is already overutilized. An attempt to delete a cell
from a partition with a high memory utilization level could take as long as 1 hour.
If the system load average is extremely high, that is, above 40, the parolrad command may time out
without initiating the operation. In that case, it would be appropriate to repeat the command,
because it will typically succeed the second time.
The system administrator should reduce the workload in the partition to a level that can be sustained
by the remaining resources before performing a cell online deactivation operation. The workload can
be reduced by redirecting network traffic to other servers, by reducing the number of interactive user
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