Re: RAC Question: What do the fields on GV$GCSHVMASTER_INFO mean?

Ernest Siu wrote:
> INST_ID: instance ID
> HV_ID: hash ID
> CURRENT_MASTER: current master instance ID
> PREVIOUS_MASTER: previous master instance ID
> REMASTER_CNT: remaster count
>
> I got description of each fields like above but the values do not make
> sense to me. For example:
>
> INST_ID: 2
> HV_ID: 453
> CURRENT_MASTER: 0
> PREVIOUS_MASTER: 1
> REMASTER_CNT: 1
>
> As I read the above, it means that for the cache block with hash value
> 453 on instance 2, the current master is 0 and previous master is 1.
> Well, there's no instance 0, but only instance 1 and 2. Does that
> mean it does not have current master? Maybe, but next we look at:
>
> INST_ID: 2
> HV_ID: 477
> CURRENT_MASTER: 0
> PREVIOUS_MASTER: 32767
> REMASTER_CNT: 1
>
> What does previous master 32767 mean? I don't think anybody have a
> 32767 node cluster?! Is it really -1? Sure but what does -1, 0 means
> when referring to instance ID? Instance IDs start from 1, 2, 3...etc.
>
> Any clue?
> Ernest

I do not know the answer, but I remind you of some common [C] programming practices:

• Arrays frequently use an offset, therefore offset '0' points to element '1';
• From new initialization, there is no 'previous' state and occasionally a value of '-1' or 'infinity' is used to indicate 'Null';
• IIRC, losing one bit of 16 as a sign bit, we could ends up with 32767 as the largest positive integer, implying infinity (also implying that RAC can not cluster more than 32766 machines).

Therefore, a supporting question question is: Is the second set of values given after a restart?

/Hans Received on Tue Feb 24 2004 - 12:56:34 CST