Oracle ASM Cluster Filesystem (ACFS)
Oracle11g Release 2 Tips by Burleson Consulting
Question: What does the AFCS do in Oracle
11gr2 and beyond Can you give an example of using AFCS?
Answer: 11gr2 introduced the
Oracle Automatic Storage Management Cluster File System (Oracle ACFS).
ASM Cluster Filesystem (ACFS) is also named "Unified Storage
Management" (UFS) and allows for storing Application File Data , the
Oracle Cluster Registry (OCR), the Cluster Voting Disk, and the Oracle
Binaries, all within ASM.
ACFS is an extension to Oracle ASM (Automatic
Storage Management) that allows customer-specific non-Oracle files to
be stored in a cluster file system. While ASM is used mainly
for the database, ACFS can now be used to store any kind of
The interesting thing is that along with the cluster file system,
Oracle has provided the facility of ACFS Snapshots for the first time,
and this is exciting news.
This is a read-only, point in time copy of an Oracle ACFS file
system, much like the NetApp snapshots we talked about in the earlier
section. Each snapshot is space-efficient and up to 63 snapshot views
are supported for each file system.
The ACFS snapshots are administered using the acfsutil
snap commands, such as acfsutil snap create and acfsutil
The Oracle ACFS snapshots can also be administered using Oracle
Enterprise Manager. When you log in to the console you will notice
that the ASM Home page that manages ASM now has an ASM Cluster File
ASM Cluster Filesystem (ACFS) in 11gR2
Answer: (by Lutz Hartmann, Oracle ACE)
There is a vulnerability exposure RAC on ASM:
"When using RAC, Oracle has announced that the key
clusterware files, the OCR and Votedisks, can now be stored in Oracle
Automated Storage Management (ASM).
However, research by our BC expert DBA's indicate
that it may well be premature to use this feature.
According to Oracle's documentation, the 11gR2
Clusterware Administration and Deployment Guide (chapter 2) , if a
single node is lost, then the entire cluster may go down, if that node
happens to be the master node."
rumors are becoming reality. Although this book is in the final
production phase already I want to take this chance to give a brief
outlook to the upcoming features for Oracle brand new release 11gR2.
All the information in this chapter is based on the documentation
for the beta release of 11gR2.
not able to test and verify all these features so there might be
some unexpected surprises. My primary intention was to give a last
minute overview of what is coming up in storage administration in
As I had already mentioned in my ASM chapter Oracle Corporation has
been working with enormous effort to create a POSIX?X OPEN based
file system for ASM storage. There were talks about it since more
than one year.
feature is called ACFS and will be available in 11gR2 for LINUX and
UNIXs. For Windows there will also be a similar solution available.
will work with Single Instance Installations as well as Clusters. It
is strongly integrated with the Oracle Clusterware. Supported
protocols for NAS are NFS and CIFS.
new feature is also named Unified Storage Management and
allows for storing the following data in ASM:
Application File Data
Cluster Registry (OCR)
Cluster Voting Disk
Now we will have all the trace files, alert.log, reports and so
forth in ASM which makes ASM a complete storage management system
finally for both database and non-database files and completely
eliminates the need for any 3rd. party cluster file
uses a journaling mechanism and uses endian independent metadata to
support large files and file systems to an extent up to exabytes. A
special metadata log structure is maintained for integrity checks
and fast recovery through a metadata transaction engine.
systems in ASM can dynamically be expended and contracted with no
downtime. High availability is fully supported through mirroring and
striping capabilities for all files now with ASM!
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