Oracle Magazine - September/October 2010

DBA
STORAGE BY ARUP NANDA

Building on Storage
Create sophisticated, feature-rich clustered file systems
on Oracle Automatic Storage Management disk groups.
ORACLE AUTOMATIC STORAGE MANAGEMENT CLUSTER FILE SYSTEM

John, the DBA at ACME Corporation, gets a unique visit from Maureen, the business
lead of the bank’s customer service applica-
tion, and her technical team. “We’re rolling
out a new Website,” explains Maureen,
“that displays images of cleared checks. We
budgeted for a dedicated image server, but
those funds evaporated with the economic
downturn. So we’d like to use our Oracle Real
Application Clusters [Oracle RAC] database
servers to also store and retrieve images.”
Keith, the lead architect, chimes in: “But
we’ve hit a roadblock. The database servers
are part of our Oracle RAC cluster, but any
images we put on one server won’t be visible
to the instances running on the other servers.
We could put them on Oracle Automatic
Storage Management disk groups as large
objects [LOBs], but our legacy systems
require a cooked—not raw—file system. We
thought of investing in a cluster file system,
but it would be prohibitively expensive.”
“In addition,” continues the lead devel-
oper, Ben, “we want to make sure a copy of
each image file is automatically saved before
it gets deleted or modified. We need these
copies to help us create a consistent set of
backup files to move to tape.”
Craig, the system architect, adds, “We
also don’t know how much space will be
required up front, and we don’t have the
money to buy a lot of disks, so we want to
be able to add storage space dynamically
without any application outages.”
John ponders these requirements.
“So what you’re saying is that you want a
regular [cooked] file system—not an Oracle
Automatic Storage Management disk group—
that’s visible across all the nodes of an Oracle
RAC cluster and is also capable of advanced
file system operations such as automatic
backup and dynamic resizing. But you want
all this without investing a single penny in a
“Precisely,” answers Maureen rather
sheepishly—keeping her fingers crossed.

grid infrastructure. With that prerequisite in place, John starts by creating an Oracle Automatic Storage Management dynamic volume. Oracle Automatic Storage Management dynamic volumes are placed in an Oracle Automatic Storage Management disk group. John uses the following SQL to scan his available disk groups to find one that has sufficient empty space:

select name, total_mb, free_mb from v$asm_diskgroup;

NAME TOTAL_MB FREE_MB —————————— —————————— ————————— ACFSDG1 152523 149908

ORACLE AUTOMATIC STORAGE
MANAGEMENT DYNAMIC VOLUMES
John points out that creating an Oracle
Automatic Storage Management Cluster
File System means first installing an Oracle
The output shows that the disk group
ACFSDG1 has about 152 GB of total capacity
and about 149 GB free. John considers this
disk group an ideal candidate for the Oracle
Automatic Storage Management volume.