IO load balance tolerance

[Paul_504]

Hi

I hope all are well. Complements of the season to one and all.

I'm faced with the following problematic question and was hoping for some input regarding this. The question is as follow:

In Tru64, load balancing/failover between fibre interfaces is on by default. Is it possible to tune this layer to adjust tolerance? How does one tune I/O timeouts at device driver level or within the LSM volume manager, and is this possible at all?

Any help regarding this, even if just pointing to documentation or something regarding this, would truly be appreciated.

I thank you in advance.
Kind regards
Paul

[Mark Poeschl_2]

The man page for 'emx' has some information on tuning the driver for the FC HBA, but I don't think there's any way to make changes on a per-HBA basis. See the section on the 'NPort_xxxxxxx' parameters.

[Han Pilmeyer]

The load balancing, multi pathing and timeout algorithms are not generally user tuneable.

Would you mind describing the problem you are trying to solve?

[Paul_504]

Hi Han

We are connected to an EMC SAN where the storage allocated to the host is mat behind multiple storage processors, however they are not in an active active configuration. And failover between the two in the event of a storage processor failure results in link lost to the host and we have found where large lun arrays are failed over we get data corruption as the time frames are too lengthy and the host reports uncorrectable read/write IOs. We were thinking of, at host level, trying to manipulate the time outs to cater for the fail over delays.

Paul

[Han Pilmeyer]

Interesting Paul. We go through large efforts to prevent data corruption in all circumstances. I don't think I fully understand what you are trying to say, but would like to discuss that further. Would you mind sending me mail at firstname dot lastname at hp dot com?

[Paul_504]

Hi Han

Will do. Thank you

Paul