Fibre Channel Addressing and Routing Fabric Configuration Process
F_S_TOV
F_S_TOV Fabric Stability Time-Out Value
Used by
Principal Switch Selection Process
Fixed Value No – Can be configured Specs – 5s (less for some vendors)
Purpose Maximum wait time for Principal Switch selection process to complete
Classes Class F
When should you change?
Might need to increase for very large fabrics, switches with slow CPUs; might be able to decrease for smaller fabrics
Consequences If ports in a fabric differ in this value, the fabric may segment.
The FC-SW specification calls for a default F_S_TOV of 5 seconds, but some vendors use shorter values.
F_S_TOV must be long enough to allow all switches to complete the selection process. In general 10 seconds, (2 x F_S_TOV), should be plenty of time for the fabric to complete selection of the Principal Switch. Even in a very large fabric with many switches, 10 seconds should still be sufficient, but if the switch CPUs are over-utilized there is a slight possibility that 10 seconds might not be long enough.
On a smaller fabric with few switches, you might want to reduce F_S_TOV to reduce the fabric build time.