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ASM Cluster Filesystem (ACFS) in
11gR2
Oracle11g Release 2 Tips by Burleson Consulting |
ASM Cluster Filesystem (ACFS) in 11gR2
by Lutz Hartmann, Oracle ACE
Note:
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."
The
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.
I was
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
11gR2.
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.
This
feature is called ACFS and will be available in 11gR2 for LINUX and
UNIXs. For Windows there will also be a similar solution available.
ACFS
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.
This
new feature is also named Unified Storage Management and
allows for storing the following data in ASM:
-
Application File Data
-
Oracle
Cluster Registry (OCR)
-
Cluster Voting Disk
-
Oracle
Binaries
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
systems.
ACFS
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.
File
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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