What's faster recovering PVlinks or Secure Path?

[Carlos F. Baladrón]

I have HP-UX 11.23 Itanium servers and a XP12000. I'd like to know what is faster recovering a failed link: LVM PVlinks or Secure Path.

I know that Secure Path has more functionalities than PVlinks, but I am only taking into account recovery time from a link failure.

Has someone made this kind of comparison before? If Secure Path doesn't offer better times I suppose we'll stick to PVlinks.

[Ted Buis · Accepted solution]

Carlos,

I don't know for sure, but I will guess SecurePath would be faster if LoadBalancing is selected. PVlinks is failover only, so it will sit there waiting a period of time before it gives up and tries the other path. SecurePath can load balance so it would seem to not have to wait, except for one I/O that might hang after a failed try for a while. Here are some notes from the SP3C install and reference guide:

"Impact of Load Balancing and Active Paths
Preferred path and selected path are meaningless designations when you have
enabled Load Balancing. Load Balancing treats all paths equally and directs I/O to
all available paths. In other words, Load Balancing is a higher priority than
preferred or selected paths.
When Load Balancing is enabled, as a default, the Secure Path for HSx driver
attempts to use all the available paths to a LUN in a round-robin fashion.
If Load Balancing is enabled and you set the path as preferred, the driver marks
the path as preferred, but the path will not be used as preferred until the Load
Balancing is turned off.
If Load Balancing is enabled and you select a path, the system performs the
following actions:
â   If the path is on the standby controller, I/O moves to the standby controller
and the selected path is one of the Active paths.
â   If the path is on the active controller, the path continues to be used as one of
the set of active paths.
This selection and marking is not preserved across reboots or power cycling."