Re: file placement and SAN

Michael Brown wrote:
>
> I have found NAS to be significantly slower, if you don't mind, how
> about posting the results of a couple of queries:
>
> SELECT * from v$SYSTEM_EVENT WHERE EVENT LIKE '%read%' OR EVENT LIKE
> '%write%';
>
> SELECT
> MIN(AVGIOTIM),MIN(MAXIORTM),MIN(MAXIOWTM),MAX(AVGIOTIM),MAX(MAXIORTM),MAX(MAXIOWTM)
> FROM V$FILESTAT;
>

Sure, except the 2nd query returns bogus results and is therefore pretty worthless for tuning. v$filestat can't be trusted on many OS's, esp. when using async i/o, multiple dbwr_io_slaves, etc. Take a look at the values and you'll see what I mean. BTW, this is 9.0.1.2.0.

EVENT                                              TOTAL_WAITS

-------------------------------------------------- -----------
-------------- ----------- ------------ -----------------
control file sequential read                            
22704              0        2356            0          23557437
control file parallel write                            
101061              0       37047            0         370471566
local write wait                                         
5269              0        1394            0          13938999
log file sequential read                                   
16              0          22            1            218414
log file single write                                      
22              0          21            1            205190
log file parallel write                                
862589              0      134140            0        1341399844
db file sequential read                                
492311              0      132453            0        1324526941
db file scattered read                                
2532523              0      737136            0        7371357522
db file parallel write                                   57412         
57412          42            0            417414
db file parallel read                                       
9              0          19            2            189860
direct path read                                       
419927              0         567            0           5665134
direct path write                                       
62802              0          57            0            565830

12 rows selected.

SQL> SQL> 2 3
MIN(AVGIOTIM) MIN(MAXIORTM) MIN(MAXIOWTM) MAX(AVGIOTIM) MAX(MAXIORTM) MAX(MAXIOWTM)

------------- ------------- ------------- ------------- -------------
-------------
   -2.142E+09             0             0    2143170914    
840044890     840046432