ResetTPRLO driver parameter

[jparnell]

Hi,

I was wondering whether anyone could give me some advice regarding the ResetTPRLO HBA driver parameter?

We're running two EVA3000s and two EVA6000s, connected are Windows 2003 servers, four of which are in two seperate Windows 2003 clusters.

A recent 'SAN health check' by HP, has recommended we check the ResetTPRLO driver parameter is set to 2 on each Windows server. Although they have recommended this is done, they haven't given us a reason, or explained what this setting actually does.

Please could someone offer some advice?

Thanks in advance.
James

[krusty]

Hi James,

The TPRLO (Third Party Process LogOut) is the way HBA's communicate with the targets they have access to (i.e. array or library). Depending on what this value is set to is how the HBA driver reacts to a command timeout or error condition. I don't remember off hand exactly what a value of "2" does, but I would recommend you do set that value for better SAN stability.

HTH,

Curt

[jparnell]

Hi Curt,
Thank you for the response. Is this value recommended for all hosts, regardless of whether they are in a MS cluster or not?
Does anyone know if this parameter is dynamic, or whether a restart is necessary?

[kris rombauts]

James,

the lputilnt.exe utility shows you this is a Dynamic parameter , so no reboot needed to change and activate new values. However pls note that you'd need to set it Permanent and or Global also in case of more then one adapter in the same system.


The readme file of the lputilnt also explains this:

- Target Reset may be used to break reservations.

By default a Target Reset will be sent when BUS_RESET() is called to clear SCSI reservations. This is the recommended way to clear Target reservations. This action is controlled by the ResetTPRLO=0
(default) registry parameter. Setting ResetTPRLO=1 will use ThirdParty Process Logout instead.
....


ResetTPRLO=n; values 0-2, default=0, ResetFF default=0
0= Send Target Reset Task Management to every logged in target device. ABTS all outstanding commands , then it sends PLOGI and PRLI. Link reinitialization is initiated only if ResetFF=1 (not recommended).

1= Send TPRLO to every logged in target device with Global Process Logout bit=1 and Type Code field=8. Link reinitialization is initiated only if ResetFF=1 (not recommended).

2= ABTS all outstanding commands, then it sends TPRLO to every logged in target device with Global Process Logout bit=1 and Type Code field=8. Link reinitialization is initiated only if ResetFF=1 (not recommended).


HTH

Kris

[krusty]

Hi James,

Kris has a great reply on the details of TPRLO settings. (BTW, I would give points ;). As far is whether it is a cluster or not, it won't matter. It is more important what you are connected to (i.e. a library would react differently than a disk array). Assuming you are using HP libraries and storage arrays, I would set the setting to 2. If you don't have both, you would have to talk with the vendor for their recommendations.

HTH,

Curt