Oracle RAC - Remastering Questions on V$GCSPFMASTER_INFO & X$KJDRMAFNSTATS

From: PD Malik <pdthedba_at_gmail.com>
Date: Thu, 28 Jul 2011 15:16:09 +0100
Message-ID: <CAHgaR1Ah45_4Q2=BNhU2j4d94tJEgyXsW3B4JLcS1bSRkWErpw_at_mail.gmail.com>



Hello experts,

Am I right in assuming that the following 2 queries should return the same result as both are presumably telling the number of objects owned by the current master? :

SQL> select count(*) from V$GCSPFMASTER_INFO where current_master=0;

COUNT(*)


217

SQL> select my_objects from X$KJDRMAFNSTATS;

MY_OBJECTS


52

Similarly, should both these queries not be returning the same result as well as both are telling the total number of remastering happened? :

SQL> select sum(remaster_cnt) from V$GCSPFMASTER_INFO;

SUM(REMASTER_CNT)


3108

SQL> select drms from X$KJDRMAFNSTATS;

DRMS


11919

(This output just for reference :

SQL> select sum(remaster_cnt) from gV$GCSPFMASTER_INFO;

SUM(REMASTER_CNT)


15544

)

Instance been up since 3rd July morning.

We've a 5 node busy 10TB 10.2.0.5 RAC on AIX 6L with around 15-16K sessions running on an average day :

SQL>select count(*) from gv$session;

  COUNT(*)


     15732

Also, just by looking at the numbers above can something be said on the amount of our remastering activity please are they normal/too high/OK etc. I understand this may be a bit vague question becs 'it depends' but still if something can be said, it'll be great.

Can I please also ask, how much stress does remastering put on background processes in particular LMS? Reason for asking is because reading Riyaj's documents it seems during Remastering, GRD only transfers a new hash table across the nodes which shudn't be a great deal (resources wise) to do and there are no actual blocks transferred between instances during remastering so wudn't have thought it would be heavy resource consuming. I am aware it does freeze the GRD for a very brief time but that shouldn't impact the normal users working who dont need GRD work at that particular time?

I am not seeing events like gc remaster or drm freeze etc. as our top events in AWR but on the other hand there have been a couple of recent CPU blips on the PROD boxes (CPU touched the floor and instances totally hung) for about 90 seconds and the top wait event for that period was 'gcs drm freeze in enter server mode' but that may be a symptom or could that be a cause due to excessive remastering please?

Thanks in advance for any help in this area please.

 :PD

--
http://www.freelists.org/webpage/oracle-l
Received on Thu Jul 28 2011 - 09:16:09 CDT

Original text of this message