NAME
fcp_large_config — define a Tachyon host bus adapter configuration as large or small
VALUES
Allowed values
0 (small)
or
1 (large)
Recommended values
0 (small)
or
1 (large)
A value of
0
defines a configuration in which an host can concurrently communicate with at most
64 ports behind any Tachyon host bus adapter.
This configuration would be considered
small.
A value of
1
defines a configuration in which a host can concurrently communicate with up
to 125 ports behind any Tachyon host bus adapter.
The maximum number of ports that may exist on a fibre channel arbitrated loop
as defined in the fibre channel standard is 126.
This configuration would be considered
large.
The fibre channel driver does not open a port to communicate with itself.
DESCRIPTION
The
fcp_large_config
tunable is a hint to the system of how many fibre channel ports may be seen
behind a Tachyon fibre channel adapter.
In the
small
(default) configuration, during startup, HP-UX will allocate
sufficient static resources to login concurrently to as many as 64 fibre
channel ports.
In a large configuration, during startup, HP-UX will allocate sufficient
static resources to login concurrently to up to 125 fibre channel ports.
Only a single fibre channel login is performed from an initiator port (host)
to a target port on an arbitrated loop.
Multiple application
open
operations may be carried across that login session.
A fibre channel logout is not performed until the last application with an
outstanding
open
does a
close.
Each initiator (host) behind the Tachyon host bus adapter attached to the
fibre channel arbitrated loop through a port must be counted when determining
how many ports are present.
Who Is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
When Should the Tunable Be Turned On?
The
fcp_large_config
tunable should be defined with a value of
1 (large)
when the number of fibre channel ports behind any Tachyon fibre channel based
adapter is greater than 64.
What Are the Side Effects of Turning the Tunable On?
The side effects of turning this tunable
on
(setting the value to
1)
would be an increased consumption of memory during HP-UX operation.
Static structures would be allocated during system startup, and the structures
would remain allocated through the life of the system.
When Should the Tunable Be Turned Off?
The
fcp_large_config
tunable should be defined with a value of
0 (off),
when the number of fibre channel ports behind any Tachyon fibre channel based
adapter is less than or equal to 64.
What Are the Side Effects of Turning the Tunable Off?
The side effects of turning the tunable
off
(setting the value to
0)
would be the default memory utilization by the Tachyon driver.
If there are more than 64 fibre channel ports behind a host bus adapter,
then the host could communicate concurrently with up to 64.
If more than 64 ports exist on the fibre, then any login attempts by the host
after 64 successful logins would wait until one of the other ports logged out.
This could give the appearance of a hung port if applications run for long
periods of time without doing
close
operations.
WARNINGS
All HP-UX kernel tunable parameters are release specific.
This parameter may be removed or have its meaning changed in
future releases of HP-UX.
AUTHOR
fcp_large_config
was developed by HP.
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