Oracle/HP Best Practices Guide for HP IO Accelerators

Single-instance performance architectures 22
end if;
end loop;
end;
/
When the script completes, the database REDO logs reside in the IO Accelerator location. Because
ASM is used, the old REDO log datafiles are automatically deleted when the corresponding REDO
log group is dropped.
3. Use the following SQL query to display the new location of the REDO logs:
select a.group# "Group Nbr",
b.thread# "Thread Nbr",
substr(a.member,1,65) "Member",
b.bytes/1048576 size_kb "Size (MB)",
b.sequence# "Seq Nbr",
b.archived "Archived",
b.status "Status"
from v$logfile a, v$log b
order by b.thread#, a.group#, substr(a.member,1,65);
Using the IO Accelerator with flash cache
Using the IO Accelerator as a flash cache target can yield significant performance benefits for read-heavy
or query-heavy workloads where not all frequently read data can fit in RAM cache. The flash cache target
enables the IO Accelerator to act as a warm data cache for reads. Using a flash cache might significantly
reduce the load imposed on other storage devices, which could also yield improved write performance.
See the Oracle website
(http://www.oracle.com/pls/db112/search?remark=quick_search&word=flash+cache) for additional
information on configuring flash cache with Oracle databases.
Prerequisites
• To use flash cache, you must be running a supported version of Linux or Solaris.
• The flash cache option is available only in Oracle Database 11gR2 and later.
Assessing flash cache performance improvements
To identify whether your current workload can benefit from adding flash cache, verify that the following
conditions are true:
• The buffer pool advisory section of either the AWR report or the STATSPACK report indicate that a
larger buffer cache can be beneficial.
• The db file sequential read is a top wait event.
• The CPUs have idle cycles.
While running a heavy workload, you can issue the top command. If CPU cycles are in the idle or io
wait categories, then those are unused CPU cycles.