Viewing ASM Disk Statistics

V$ASM_DISK_IOSTAT displays information about disk I/O statistics for each ASM client.
If V$ASM_DISK_IOSTAT is queried from a database instance, only the rows relating to that instance are shown.
ASMCMD lsdsk --statistics shows just the disk statistics.
ASMCMD iostat shows a subset of the statistics depending on the option.

SQL> SELECT INSTNAME, G.NAME DISKGROUP, SUM(READS) READS,

  2    SUM(BYTES_READ) BYTES_READ, SUM(WRITES) WRITES,

  3    SUM(BYTES_WRITTEN) BYTES_WRITTEN

  4  FROM V$ASM_DISK_IOSTAT I, V$ASM_DISKGROUP G

  5  WHERE I.GROUP_NUMBER = G.GROUP_NUMBER

  6  GROUP BY INSTNAME, G.NAME;

The following query quickly shows the presence of any I/O errors reported by ASM. If this query returns a value other than zero, further investigation may be undertaken:

SQL> SELECT SUM(READ_ERRS)+SUM(WRITE_ERRS) ERRORS

  

             2  FROM V$ASM_DISK;