The ASM stripe size is defined by the hidden parameter _asm_stripesize and defaults to 128KB. This value is used by files that have the fine grained striping option set in the ASM file template.
In ASM 10g, control files, redo log files and flashback log files all feature fine grained striping. In ASM 11g and 12c, only control files have fine grained striping.
Files that do not use fine striping are considered coarse. Coarse striping is the size of the AU. We can review which files use which setting in the V$ASM_TEMPLATE view:
SQL> select name, stripe from V$ASM_TEMPLATE;
19 rows selected.
Dell EMC has observed a 7 percent to 12 percent performance improvement from setting redo logs to fine grained striping of 128 KB.
To change the striping from coarse to fine or vice-versa, the DBA can modify the ASM diskgroup template as follows:
SQL> ALTER DISKGROUP MYDATA ALTER TEMPLATE onlinelog ATTRIBUTES (FINE);
Dell EMC recommends setting the template for redo log files and temp files to fine, and leaving the ASM stripesize at 128 KB.