I will be installing 11.20.3 Database in Aix 6.1 - I'am worry about the fs blocksize and redo blocksize

LindaC
LindaC used Ask the Experts™
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Hi experts.
I will be installing 11.20.3 Database in Aix 6.1 - I'am worry about the fs blocksize and redo blocksize.

We have a lot of db's with I/O problems and maybe the way the filesystems are created can be a issue?

Also I wonder if a redo of 4k can be more efficient than the default of 512?
We have a similar db in 11.2 and also Ibm Aix 6.1 and this is the wastage:

SQL> conn system
Enter password:
Connected.
SQL> SELECT BLOCKSIZE FROM V$LOG;

 BLOCKSIZE
----------
       512
       512
       512

SQL> SELECT name, value FROM v$sysstat WHERE name = 'redo wastage';

NAME                                                                  VALUE
---------------------------------------------------------------- ----------
redo wastage                                                     1386749364
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Almost for sure You should select bigger block sizes (like 4K). Depending on Your activities in the database, even the bigger block sizes could be necessary.

See the oracle documentation for more information about advantages and disadvantages of the different block sizes.
http://docs.oracle.com/cd/E11882_01/server.112/e10821/iodesign.htm#g35558

I just wonder: if You use filesystems on AIX instead of ASM, do You have CIO option activated there? Start "mount"  command and see, if "cio" is in the list

Author

Commented:
datamartdev-oracle:/home/oracle> mount
  node       mounted        mounted over    vfs       date        options
-------- ---------------  ---------------  ------ ------------ ---------------
         /dev/hd4         /                jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/hd2         /usr             jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/hd9var      /var             jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/hd3         /tmp             jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/hd1         /home            jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/hd11admin   /admin           jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /proc            /proc            procfs Apr 12 12:09 rw
         /dev/hd10opt     /opt             jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/livedump    /var/adm/ras/livedump jfs2   Apr 12 12:09 rw,log=/dev/hd8
         /dev/martdev_orac_lv /oracle          jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_data_lv /martdev/DATA    jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_indx_lv /martdev/IDX     jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_red1_lv /martdev/REDO1   jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_red2_lv /martdev/REDO2   jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_red3_lv /martdev/REDO3   jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_syst_lv /martdev/SYSTEM  jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_temp_lv /martdev/TEMP    jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_undo_lv /martdev/UNDO    jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_dump_lv /dump_ora/martdev jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/martdev_arch_lv /martdev/ARCHIVES jfs2   Apr 16 09:39 rw,log=/dev/loglv00
         /dev/backup_lv   /backup          jfs2   Apr 18 11:18 rw,log=/dev/loglv00
datamartdev-oracle:/home/oracle>
OK, "cio" is not in the list of the FS options. I've asked, because combination of "cio" and Oracle file autoextending could cause massive performance problems on AIX.

Anyway, looks like this is not Your case.

Consider about increasing the block size at least to 4K.
Commented:
Sorry. This question was answered in this posting:

The redo log needs to oracle decide about the size based on the internal disk sector size.
If they are not emulating 4k then let oracle create the redo log with 4k, if internal sector sizes are indeed 4k then in version 11.2 you can create the redo with 4k.  If sector size is 512 bytes then let oracle create them with blocksize of 512 bytes.

http://www.experts-exchange.com/Database/Oracle/Q_27682006.html

http://www.rampant-books.com/art_sharma_redo_log_blocksize.htm

Author

Commented:
See my previous comment/post

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