Thursday, January 28, 2010

ACFS: NOT for Database Files!

ASM Cluster File System was introduced with Grid Infrastructure along with Oracle 11g Release 2. To be honest, I assumed this file system layer was also provided to store database files, a kind of improvement, because ASM, being a black box to many, 'hided' these database files from sight on the Operating System. Which - on the other side - was kind of neat, because chances were lowered these files to be accidentally removed by non-knowledgable users.

It is technically possible to store your database files on ACFS, no question about that. I already deployed a number of test databases on ACFS. However, the Oracle 11g Release 2 Storage Administrator's Guide, Chapter 5 states:

  • Oracle ASM is the preferred storage manager for all database files. It has been specifically designed and optimized to provide the best performance for database file types.

  • Oracle ACFS is the preferred file manager for non-database files. It is optimized for general purpose files.

  • Oracle ACFS does not support any file that can be directly stored in Oracle ASM.

    Not supported means Oracle Support Services will not take calls and development will not fix bugs associated with storing unsupported file types in Oracle ACFS.

Especially that last sentence says it all: If you run into trouble with your database stored on ACFS, you will not be assisted by Oracle Support.

Here is the list of file types that are NOT supported to be stored on ACFS:

Control files
Data files
Redo log files
Archive log files
Temporary files
Data file backup pieces
Data file incremental backup pieces
Archive log backup piece
Data file copy
Persistent initialization parameter file (SPFILE)
Flashback logs
Change tracking file
Data Pump dumpset
Automatically generated control file backup
Cross-platform transportable data files
Flash file
Oracle ASM Persistent initialization parameter file (SPFILE)
Oracle Cluster Registry file

Be aware of this when you are designing your Grid Infrastructure!


  1. Thanks for the update on this. At first when I heard about ACFS, I didn't think of the fact that this is not intended to store datafiles. I expected the file system like GPFS, CFS, etc.

    Regards, Gerwin

  2. Thanks for stopping by, Gerwin!
    Similar with me. I actually was quite surprised to see this documented(!) limitation. On the other hand, one might consider it quite reasonable, seeing how ASM has been positioned.

  3. [oracle@node1 ~]$ sqlplus "/ as sysdba"

    SQL*Plus: Release Production on Thu Nov 25 10:08:16 2010

    Copyright (c) 1982, 2010, Oracle. All rights reserved.

    Connected to:
    Oracle Database 11g Enterprise Edition Release - 64bit Production
    With the Partitioning, Real Application Clusters, Automatic Storage Management and Real Application Testing options

    SQL> archive log list;
    Database log mode Archive Mode
    Automatic archival Enabled
    Archive destination /u01/app/acfsmounts/data_vltest
    Oldest online log sequence 31
    Next log sequence to archive 33
    Current log sequence 33
    SQL> select name from v$datafile;


    6 rows selected.

    SQL> !mount
    /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
    proc on /proc type proc (rw)
    sysfs on /sys type sysfs (rw)
    devpts on /dev/pts type devpts (rw,gid=5,mode=620)
    /dev/sda1 on /boot type ext3 (rw)
    tmpfs on /dev/shm type tmpfs (rw)
    none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
    sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
    oracleasmfs on /dev/oracleasm type oracleasmfs (rw)
    /dev/hda on /media/cdrom type iso9660 (ro)
    /dev/asm/vltest-51 on /u01/app/acfsmounts/data_vltest type acfs (rw)

  4. Hi!

    Starting with Oracle Automatic Storage Management 11g Release 2 (, Oracle ACFS supports RMAN backups (BACKUPSET file type), archive logs (ARCHIVELOG file type), and Data Pump dumpsets (DUMPSET file type). Note that Oracle ACFS snapshots are not supported with these files.

    1. I read about that too. that's controversial or could it be Oracle realised if there's nothing great about ACFS that it will not gain popularity thus in newer version they starting to certify more DB files there.

      But the question back, Oracle going to support or not? Also I run into patching issues using Opatch auto. Apparently it requires a share directory that can be seen by all nodes. We could use ACFS for this purpose.