Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Usenet -> c.d.o.server -> 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_WAITSTOTAL_TIMEOUTS TIME_WAITED AVERAGE_WAIT TIME_WAITED_MICRO
-------------------------------------------------- ----------- -------------- ----------- ------------ ----------------- 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 840046432Received on Thu Apr 25 2002 - 15:48:47 CDT