Some doubts in Persistent Reservation

Some doubts in Persistent Reservation

[djshetty]

Hi,

I have been trying to understand PERSISTENT RESERVATION as per SCSI SPC-3
standards. I had the following two doubts:
   1. Is persistent reservation applied on a target port or on a particular
LUN connected to a target port. The SCOPE of persistent reservation says
"Entire LOGICAL UNIT", whereas the registration is done for a target PORT.
Hence the confusion.
   2. Is there any precise use of the PRGeneration key? I guessed it must be
used for knowing whether any changes have been on the target (with regards
to persistent reservation) since the previous command executed. 

Regards,
Dhiraj.
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Re: Some doubts in Persistent Reservation

[James Bottomley]

On Thu, 2006-11-23 at 23:55 -0800, djshetty wrote:
>    1. Is persistent reservation applied on a target port or on a particular
> LUN connected to a target port. The SCOPE of persistent reservation says
> "Entire LOGICAL UNIT", whereas the registration is done for a target PORT.
> Hence the confusion.

For multi-ported devices it's per LUN per port (unless you specify all
target ports).

>    2. Is there any precise use of the PRGeneration key? I guessed it must be
> used for knowing whether any changes have been on the target (with regards
> to persistent reservation) since the previous command executed. 

That's the stated use in section 5.6.5.3 of SPC-3, yes.

James