RE: interpret v$mts
- From: "MacGregor, Ian A." <ian@xxxxxxxxxxxxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 2 Jun 2004 07:03:20 -0700
It would be helpful to know what is slow. Is it a query? Is it DML? Has the
operation been traced. One cannot reduce all performance problems in an MTS
environment to the need for more shared servers.
There is the possibility that the system is not suitable for MTS at all. MTS
is meant for OLTP systems running properly tuned queries with small return
sets, ideally one row. Other queries can tie-up shared servers for long
periods of time, resulting in the need for more of them. If this is what's
going on the choice to use MTS over dedicated servers needs to be re-examined.
You can also look at having two connect strings, one for true OLTP operations
and another with "server=dedicated" for your reporting queries.
MTS is to be avoided unless absolutely!! necessary. Has the number of
simultaneous connetions to be supported been dtermined. Has the private memory
needs for a shadow process been examined. Is the SGA properly tuned?
Ian MacGregor
Stanford Linear Accelerator Center
ian@xxxxxxxxxxxxxxxxx
-----Original Message-----
From: Jeroen van Sluisdam [mailto:jeroen.van.sluisdam@xxxxxxxxxx]
Sent: Monday, May 31, 2004 11:02 PM
To: 'oracle-l@xxxxxxxxxxxxx'
Subject: RE: interpret v$mts
Hi,
Just looking at these statistics is not enough Is the problem in the
dispatchers or the servers?
Try monitoring busy rate and available servers in this period. Anything known
about the scope of this problem all users concerned?
Regards,
Jeroen
My set of sql to show mts info
set term off
set feedb off head on
col network heading 'Protocol' format A50 justify c
col busy_rate heading 'Busy Rate %' format 990.0 justify right
set term on
PROMPT Network statistics
Prompt
Prompt Busy rate should not be more then 50% select network,
sum(busy)*100 / (sum(busy) + sum(idle)) busy_rate
from v$dispatcher
group by network
/
set head off
PROMPT
Prompt
Prompt There should be servers and dispatchers waiting for new requests:
select 'Dispatchers ' ||status, count(STATUS)
from v$dispatcher group by status / select 'Shared
servers:'||status,count(status)
from v$shared_server group by status / set head on
select * from v$mts;
exit
-----Oorspronkelijk bericht-----
Van: Barbara Baker [mailto:barbarabbaker@xxxxxxxxx]
Verzonden: Friday, May 28, 2004 11:42 PM
Aan: oracle-l@xxxxxxxxxxxxx
Onderwerp: interpret v$mts
Dick (if you're out there) or someone who understands
this mts stuff:
We're still having problems with slowness. I know you
told me to just keep adding servers till the screaming
stopped. I didn't listen too carefully. . .
I'm wondering if you can tell me if I'm interepreting
this correctly. mts_servers is set to 30. At 10:09
this morning, my servers_highwater was 34. Here's
select * from v$mts at 10:09
MAXIMUM_CONNECTIONS : 894
MAXIMUM_SESSIONS : 893
SERVERS_STARTED : 4
SERVERS_TERMINATED : 4
SERVERS_HIGHWATER : 34
-----------------
at 10:49, looked like this:
MAXIMUM_CONNECTIONS : 936
MAXIMUM_SESSIONS : 936
SERVERS_STARTED : 37
SERVERS_TERMINATED : 37
SERVERS_HIGHWATER : 52
-----------------
So does that mean that in 40 minutes, it started 33
servers? If so, isn't that, like, obscene??
I assume there's overhead associated with starting up
these servers. Should I be setting mts_servers to
something extremely high (like around 50)? It was
within this 40 minutes that we saw extreme slowness.
I don't know if I'm looking cause or effect, but it
seems pretty strange to me that we needed an
additional 30 servers in a 40 minute period.
Thanks for any advice on this one.
Barb
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