To enable restart optimization algorithms, use the
fcdomain optimize
command. To disable these algorithms, use the no form of this command.
fcdomain optimize
{
fast-restart
| selective-restart
| scale-restart
| all
}
vsan
ID
no fcdomain optimize
{
fast-restart
| selective-restart
| scale-restart
| all
}
vsan
ID
Syntax Description
|
fast-restart
|
Enables domain manager fast restart.
|
|
selective-restart
|
Enables domain manager selective restart.
|
|
scale-restart
|
Enables domain manager scale restart.
|
|
all
|
Enables all domain manager optimizations.
|
|
vsan
ID
|
Specifies the VSAN ID. Range is 1–4093.
|
Command Default
Scale restart optimization is enabled by default.
Command Modes
Configuration mode (config)
Command History
|
Release
|
Modification
|
|
6.2(9)
|
Added the
all
and
scale-restart
keywords to the syntax description.
|
|
3.0(2)
|
Added the
fast-restart
keyword to the syntax description.
|
|
1.1(1)
|
This command was introduced.
|
Usage Guidelines
In the Fibre Channel protocol, fabric reconfiguration starts with flooding of reconfigure fabric (RCF) or build fabric (BF)
frames which indicates to all the switches in the VSAN that the fabric is changing. This process is followed by principal
switch selection and domain ID allocation phases. Fibre Channel domains can be started disruptively or nondisruptively. A
disruptive restart sends RCF frames to the other switches in the VSAN and data traffic is disrupted on all the switches in
the VSAN (including remotely segmented ISLs). A nondisruptive restart sends BF frames to the other switches in the fabric
and data traffic is disrupted only on the local switch. The MDS platform has a number of optimizations available to increase
scaling and the completion speed of this process.
When fast restart is enabled and a backup link is available, the domain manager needs only a few milliseconds to select a
new principal link to replace the one that failed. Also, the operation to select the new principal link is only executed by
the two switches that are directly attached to the failed link, not all switches in the VSAN. When a backup link is not available,
the domain manager reverts to the default behavior and starts a normal build fabric phase followed by a principal switch selection
phase.
When selective restart is enabled, the domain manager sends BF frames on only one peer switch link if there are multiple links
between them. This benefits scaling. During the build fabric phase, frames are normally flooded on all links. A switch may
have more than one link to a peer switch. In such cases, the BF frame can be sent to only one of the links to the peer switch.
This configuration reduces the number of BF frames that are to be exchanged during the build fabric phase of fabric reconfiguration.
When scale restart is enabled, a single consolidated Exchange Fabric Parameter (EFP) request will be flooded by the principal
switch after the domain identifier allocation phase is completed. Normally, when principal switch assigns a domain ID to a
switch (including itself) during the fabric reconfiguration phase, it transmits an Exchange Fabric Parameter (EFP) request.
This request carries the domain list information of the fabric. Whenever the domain list changes, an EFP frame is flooded
to the fabric. This option reduces the number of EFP requests each switch must process. Scale restart is enabled by default
in all native VSANs. This option is not supported in interoperability mode and thus is not enabled in interoperability VSANs.
We recommend using the
fast-restart
option on most fabrics, especially those with many logical ports (3200 or more), where a logical port is an instance of a
physical port in a VSAN.
Examples
The following example displays how to enable domain manager fast restart on VSAN 10:
switch# configure
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# fcdomain optimize fast-restart vsan 10
The following example displays how to disable domain manager fast restart on VSAN 10:
switch# configure
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# no fcdomain optimize fast-restart vsan 10
The following example displays how to enable all domain manager optimizations on VSAN 10:
switch# configure
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# fcdomain optimize all vsan 10
The following example displays how to disable all domain manager optimizations on VSAN 10:
switch# configure
Enter configuration commands, one per line. End with CNTL/Z.
switch(config)# no fcdomain optimize all vsan 10
