Dell POWEREDGE M1000E - Manual (Page 523)

Fabric OS Administrator’s Guide 523
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QoS zone-based traffic prioritization
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Set CSCTL QoS Mode to 1 to enable auto mode, establishing the settings shown in Table 78 on
page 521. Set CSCTL QoS Mode to 0 to disable auto mode and revert to default settings, shown in
Table 77 on page 521.
NOTE
As noted previously, this is a chassis-level configuration. It does not provide options to enable
CS_CTL QoS on the ports.
Considerations for using CS_CTL-based frame prioritization
To use CS_CTL for QoS on a given port for a given flow, proceed as follows:
1. Determine whether to use the default mode (see Table 77 on page 521) or the auto mode (see
Table 78 on page 521). No choice results in the default mode.
2. In either case, ensure that the switch port connected to the initiator host and the switch port
connected to the target host have csctl_mode enabled, as in “Enabling and disabling
CS_CTL-based frame prioritization on ports” on page 522.
QoS zone-based traffic prioritization
QoS zone-based traffic prioritization allows you to categorize the traffic flow between a host and
target as having a high or low priority. For example, you could assign online transaction processing
(OLTP) to high priority and backup traffic to low priority.
All flows without QoS prioritization are considered medium priority.
High-, medium-, and low-priority flows are allocated to different virtual channels (VCs). High-priority
flows receive more fabric resources than medium-priority flows, which receive more resources than
low-priority flows.
NOTE
If there is a single low-priority flow to a destination ID (DID) and several medium-priority flows to that
same DID, then it is possible that the medium-priority flows would have less bandwidth. This is
because they have to share the medium-priority fabric resources, whereas the low-priority flow would
have a separate set of fabric resources for its exclusive use.
Trunking considerations before you install the Adaptive Networking
license
NOTE
This section applies only to 8-Gbps and 16-Gbps ports that are not long-distance ports.
If ports are part of an active trunk group before the Adaptive Networking license is added, ISLs are
formed without QoS.
When you install the Adaptive Networking license, QoS is automatically enabled on all ports for which
you have not manually disabled QoS, as the ports in the trunk group are set to QoS enabled by default.
Adding the license does not immediately affect the trunk groups, however. The trunks continue to
operate without QoS until the next time one of the ISLs is toggled, at which point the toggled ISL
comes up with QoS enabled and splits from the trunk group because of a QoS mismatch.