HP 3PAR OS 3.1.3 CLI Administrator's Manual

Executing the QoS CLI commands requires a logon to an account with Super or Edit rights. Any
role granted the qos_set right can set QoS configurations. QoS rules can be scheduled using the
createsched command for automated QoS policy changes for example to adapt to day/night or
weekday/weekend workload conditions.
The HP 3PAR CLI command, srstatqos, displays historical performance data reports for the
QoS rules. This command is integrated in HP 3PAR System Reporter (SR) on the 3PAR nodes. SR
3.1 MU1, installed on a separate server, includes statistics on QoS. To learn more about the QoS
information in SR, see the HP 3PAR System Reporter 3.1 Software User's Guide and the HP 3PAR
System Reporter Software Release Notes.
Removing a QoS Rule
To clear a QoS rule, issue the setqos –clear vvset:<vvset> command, where <vvset>
is the name of vvset the QoS rule is cleared of. Clearing a QoS rule does not require first disabling
the rule. Clearing the QoS rule deactivates an enabled rule. A QoS rule can be enabled and
disabled at any moment. Once a QoS rule is disabled, the IOPS and bandwidth for the VVs in the
VVset increases (if they were being delayed by the rule).
Managing QoS Rules
There is no limitation on the minimum number of IOPS and bandwidth that can be set on a given
VVset QoS Rule. It is important that the workloads of the various applications be fully understood
before applying a QoS rule. HP 3PAR System Reporter can be used to make this determination.
The following best practices provide general guidelines only.
Assembling VVs into VVsets
VVsets group virtual volumes logically. Use cases for VVsets include taking simultaneous point-in-time
virtual copies of multiple volumes, and creating Remote Copy volume groups for write consistency
during replication operations.
Volumes that belong together because they are owned by the same application or because they
belong in the same virtual domain should be included in the same VVset. Even if a number of
virtual volumes are unrelated and do not need write consistency, you can group them to a VVset
so as to reduce the administrative overhead when managing them. This way the I/O profile of the
volumes can be managed by a single QoS rule for their parent VVset.
VVsets are especially useful in the deployment of HP 3PAR Priority Optimization, because QoS
rules in HP 3PAR Priority Optimization are defined on VVsets. HP strongly encourages the creation
of VVsets and group volumes logically on HP 3PAR StoreServ storage systems.
Determining the Values for IOPS and Bandwidth for a System
HP 3PAR Priority Optimization’s QoS rules define limits for IOPS and bandwidth in absolute
numbers, not percentages. Because of this, the QoS administrator needs reasonably accurate data
on the system’s maximum I/O and throughput capability as well as an accurate understanding of
actual I/O and throughput workloads to the volumes that will have QoS applied to them.
HP Presales can estimate the maximum front-end workload for a system in IOPS and bandwidth,
assuming a particular I/O size and a given ratio for read/write I/Os. With this information, QoS
rules can be defined per workload, ensuring that the total sum of IOPS or bandwidth does not
exceed what is sustainable by the system configuration if no oversubscription is allowed. Re-analysis
of the system’s capability and re-adjustments of the limit values for any existing QoS rules must
take place in the following cases:
• When upgrading the storage system with additional disk drives and/or nodes.
• When making use of additional FC and/or iSCSI interface cards to the storage system.
• When adding additional physical hosts of virtual machines with extra workloads to the storage
system.
Using HP 3PAR Priority Optimization 155