RE: Log writer

From: Mohan, Ross <MohanR_at_STARS-SMI.com>
Date: Thu, 22 Mar 2001 09:30:37 -0800
Message-ID: <F001.002D4FAD.20010322092038@fatcity.com>

Kev,

Pure
shot from hip:

I'd
say you have more network/app response tuning than log tuning. I'd
say
you have more disk tuning ( for table/index reads) than log tuning. I

would
DEFINITELY turn the silly ass MTS off.

I'd
find out how to make sure disk cache is 4 MB and is writeBACK
not
writeTHRU. ( if either ) I'd have questions about the controller, too, but.."later".

(You
didn't tell me the size of the redo log buffer...)

Of
course, having a two disk wonder (or whatever it is) is the number
one
thing to work on.

In any
case, with your hardware, your system should easily be able to
handle a few users, in its sleep.

There's about two dozen little tweaks you can do to perk things up a bit,

but
basically, your "rock and a hard place" is going to be a two disk wonder
on a
single controller...

hth

Ross



-----Original Message-----From: Kevin Kostyszyn [mailto:kevin_at_dulcian.com]Sent: Thursday, March 22, 2001 11:31 AMTo: Multiple recipients of list ORACLE-LSubject: RE: Log writer
 Jeez, Seagate Cheeta 18 and 36, 10k RPM ahhh
 UNFORMATTED CAPACITY (GB)

  ________________22.54       FORMATTED 
  CAPACITY (GB) __________________18.21       
  AVERAGE SECTORS PER TRACK ________________213 rounded

down ACTUATOR TYPE

  ____________________________ROTARY VOICE

COIL TRACKS

  ___________________________________167,008       
  CYLINDERS ________________________________6,962

user HEADS

  ______PHYSICAL______________________24

DISCS (3 in)

  _____________________________12       MEDIA 
  TYPE _______________________________THIN

FILM/MR RECORDING METHOD

  _________________________PRML 8/9 PR4

  INTERNAL TRANSFER RATE (mbits/sec)________152 to   231       EXTERNAL TRANSFER RATE (mbyte/sec)   _______40
  Sync            Low
  Voltage Differential(LVD) _______80
  Sync       SPINDLE SPEED (RPM)

  ______________________10,025       AVERAGE 
  LATENCY (mSEC) ___________________2.99

BUFFER (/optional)

  _______________________1MB/4MB

Read Look-Ahead, Adaptive,

I believe the only problem is
 that they are on one controller. However, this is not a huge database, only about 3-4 users connected at a time, but lots of DML. The machine is a Dell Precision 410 with a gig of Ram and dual PIII 450's. I don't think that it's a huge problem, but it does keep coming up. There are three log file groups of 32 MB's each and yes the database is also spread accross these two platters.

 Oh and the
 results......YOINK!

 rdbms ipc

  message

14980809SQL*Net message from

  client

9595869pmon

  timer

1880177virtual circuit

  status

1877869smon

  timer

1875449dispatcher

  timer

1874318SQL*Net break/reset to

  client

49746control file parallel

  write

18026db file sequential

  read

3947log file

  sync

1456db file scattered

  read

1017

 <FONT face=Arial color=#0000ff

  size=2>EVENT                                                            
  TIME_WAITED----------------------------------------------------------------

-----------log file parallel

  write

616Null

  event

411library cache

pin

315refresh controlfile

  command

292reliable

  message

273rdbms ipc

  reply

146control file sequential

  read

108log file switch

  completion

58SQL*Net more data to

  client                                               
  45enqueue

27file

  identify

24

 <FONT face=Arial color=#0000ff

  size=2>EVENT                                                            
  TIME_WAITED----------------------------------------------------------------

-----------log file single

  write

23latch

  free

19SQL*Net message to

  client

17file

  open

16buffer busy

  waits

13SQL*Net more data from

  client

6direct path

  read

5log file sequential

  read

0db file parallel

  write

0instance state

  change

0direct path

  write

0

 <FONT face=Arial color=#0000ff

  size=2>EVENT                                                            
  TIME_WAITED----------------------------------------------------------------

-----------LGWR wait for redo

  copy

0
 
 Which ya think master Ross?
 
 Kev
 
 
 -----Original Message-----From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of Mohan, RossSent: Thursday, March 22, 2001 11:02 AMTo: Multiple recipients of list ORACLE-LSubject: RE: Log writer

Disk mfr? rpm? seek/access times? diskperf -y set already? CPU,I/O, or diskbound system? log buffer size? log file size? what else is on the "separate" disks? anything? separate disks share a controller? select event, time_waited from v$system_event order by 2 desc; results? just a few questions that come to mind.... -----Original Message----- From:
 Kevin Kostyszyn [<A
 href="mailto:kevin_at_dulcian.com">mailto:kevin_at_dulcian.com] Sent: Thursday, March 22, 2001 8:50 AM To: Multiple recipients of list ORACLE-L Subject: Log writer
 Hi all,
 I am testing out
 Spotlight on Oracle from Quest Software. It is telling me that my log writer process is slow. What it looks like it is saying is that most disks take about 20ms to right the data and mine is taking on average about 40ms. I don't know why, they are scsi drives and there isn't that much stress on the syste. Anyway, I moved the redo logs to seperate disks, but I fear I may have made an error. Instead of moving each "group" to seperate hard disks, I moved the members of each group to seperate hard disks. Anyway, I am wondering if anyone has advice on this problem.
 Sincerely, Kevin Kostyszyn
 DBA Dulcian, Inc www.dulcian.com kevin_at_dulcian.com

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Received on Thu Mar 22 2001 - 11:30:37 CST