Home > Workload Solutions > Oracle > White Papers > Oracle ASM on ScaleIO Best Practices > ASM stripesize, coarse, and fine grained striping
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;
NAME STRIPE
------------------------------ ------
PARAMETERFILE COARSE
ASMPARAMETERFILE COARSE
ASMPARAMETERBAKFILE COARSE
DUMPSET COARSE
CONTROLFILE FINE
FLASHFILE COARSE
ARCHIVELOG COARSE
ONLINELOG COARSE
DATAFILE COARSE
TEMPFILE COARSE
BACKUPSET COARSE
AUTOBACKUP COARSE
XTRANSPORT COARSE
CHANGETRACKING COARSE
FLASHBACK COARSE
DATAGUARDCONFIG COARSE
OCRFILE COARSE
OCRBACKUP COARSE
ASM_STALE COARSE
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);
Diskgroup altered.
Dell EMC recommends setting the template for redo log files and temp files to fine, and leaving the ASM stripesize at 128 KB.