Re: received more blocks than served?

From: Dan Norris <dannorris_at_dannorris.com>
Date: Tue, 08 Jul 2008 11:21:32 -0600
Message-ID: <4873A21C.5090003@dannorris.com>

I think Mark's suggestion about the different start times is probably the culprit. Flawed logic on my part--thanks Mark for pointing it out. Guess I was having a Monday :-|

Dan

Á¶µ¿¿í wrote:

Can you compare the result
- with the total summation of "received" and "served" blocks, including cr blocks?
- and with the summation of cr blocks only?

Dion Cho

2008/7/8 <dannorris@dannorris.com>:

I have a 3-node 10.2.0.3 RAC cluster on RH4. I was looking for
verification that I hadn't dropped any blocks between instances during GC
operations. So, I wanted to get a sum of all blocks sent, a sum of all
blocks received and they should be very close to equal.

What I see below has me perplexed. How can there be more blocks received
than served? That is, how can an instance receive more information than
was sent? Can a single block be served to multiple destinations? I don't
think so, but maybe that's where the magical block synthesis is coming
from?

It's a 3-node cluster, so there's no easy 1-to-1 mapping to be done.

I'm open for ideas...

 1  select sum(b2.value) "GCS CURR BLOCKS RECEIVED",
 2  sum(b1.value) "GCS CURR BLOCKS SERVED",
 3  (sum(b1.value)-sum(b2.value)) "SERVED - RECEIVED"
 4  from gv$sysstat b1, gv$sysstat b2
 5  where b1.name = 'gc current blocks served'
 6  and   b2.name = 'gc current blocks received'
 7* and   b1.inst_id = b2.inst_id

GCS CURR BLOCKS RECEIVED GCS CURR BLOCKS SERVED    SERVED - RECEIVED
------------------------ ---------------------- --------------------
              628072519              622037942             -6034577

Dan



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-- http://www.freelists.org/webpage/oracle-l Received on Tue Jul 08 2008 - 12:21:32 CDT