
Fabric OS 5.3.0 administrator guide 219
NOTE:
Certain devices do not tolerate out-of-order exchanges; in such cases, use the port-based routing
policy.
In a stable fabric, frames are always delivered in order, even when the traffic between switches is shared
among multiple paths. However, when topology changes occur in the fabric (for example, if a link goes
down), traffic is rerouted around the failure, and some frames could be delivered out of order. Most
destination devices tolerate out-of-order delivery, but some do not.
Use of out-of-order frame-based delivery can minimize the number of frames dropped, while enabling
in-order delivery (IOD) guarantees that frames are either delivered in order or dropped. All HP B-series
switches enable IOD by default to ensure frames are delivered in order, as not all HP destination devices
can tolerate out-of-order frames.
To disable in-order frame delivery across topology changes
1.
Connect to the switch and log in as admin.
2.
At the command line, enter the
iodReset
command.
NOTE:
This command can cause a delay in the establishment of a new path when a topology change
occurs; use it with care.
3.
To confirm In Order Delivery has been disabled, issue the
iodShow
command.
To restore in-order frame delivery across topology changes
1.
Connect to the switch and log in as
admin
.
2.
Enter the
iodSet
command at the command line.
Using Dynamic Load Sharing
The exchange-based routing policy depends on the Fabric OS Dynamic Load Sharing feature (DLS) for
dynamic routing path selection. When using the exchange-based routing policy, DLS is by default enabled
and cannot be disabled. In other words, you cannot enable or disable DLS when the exchange-based
routing policy is in effect.
When the port-based policy is in force, you can enable DLS to optimize routing. When DLS is enabled, it
shares traffic among multiple equivalent paths between switches. DLS recomputes load sharing when a
switch boots up or each time an E_Port goes offline and online, or a Fx_Port goes offline.
To check and set DLS
1.
Connect to the switch and log in as admin.
2.
Enter the
dlsShow
command to view the current DLS setting.
One of the following messages appears:
• “DLS is set” indicates that dynamic load sharing is turned on.
• “DLS is not set” indicates that dynamic load sharing is turned off.
• “DLS can not be changed with current routing policy” indicates that you are using the
exchange-based routing policy and you cannot enable or disable DLS.
3.
Enter the
dlsSet
command to enable DLS or enter the
dlsReset
command to disable it.
switch:admin>
dlsshow
DLS is not set
switch:admin>
dlsset
switch:admin>
dlsshow
DLS is set
switch:admin>
dlsreset
switch:admin>
dlsshow
DLS is not set
Summary of Contents for AA979A - StorageWorks SAN Switch 2/8V
Page 1: ...HP StorageWorks Fabric OS 5 3 x administrator guide Part number 5697 0244 November 2009 ...
Page 16: ...16 ...
Page 20: ...18 ...
Page 24: ...24 Introducing Fabric OS CLI procedures ...
Page 116: ...118 Maintaining configurations ...
Page 170: ...172 Managing administrative domains ...
Page 200: ...202 Installing and maintaining firmware ...
Page 222: ...224 Routing traffic ...
Page 274: ...286 Administering FICON fabrics ...
Page 294: ...306 Working with diagnostic features ...
Page 350: ...362 Administering Extended Fabrics ...
Page 438: ...440 Configuring the PID format ...
Page 444: ...446 Configuring McData Open Fabric mode ...
Page 450: ...452 Understanding legacy password behaviour ...