Sunday, May 8, 2011

Summary of Methods to Protect Archive Log Tapes

I have a client who is concerned about losing archive logs in between full RMAN database and archive log backups, in the event of a loss. I was asked to provide options which I am sharing on this blog. The environment is AIX 6.5 and Oracle 11.2 Standard Edition. Please feel free to comment and share your suggestions.

Options to protect archive log tapes (and the full database) are:

I. Have RMAN take more frequent backups, including archive logs.

II. Oracle allows specification of an alternate destination for archive
logging that is additional to the primary destination.

So, NFS mount a directory on a remote server and use an alternate
“archive_log_dest_1” parameter to specify the NFS mounted remote
directory as the alternate log destination.

III. SFTP or rsynch a copy of the archive logs to a remote server through
a shell script. The shell script would have to:

1. check the V$ARCHIVED_LOG view to determine if each archive log
file in the archive log directory has completed the archiving
2. use the rsynch command, or SFTP, to synchronize the remote
archive log destination with the primary server archive log
3. run this script every "nn" time intervals, leaving a window for
the RMAN backups

IV. Use the pre-RMAN method of database backup. Copy the database user
datafiles, control files, archive logs and parameter file to a
directory on a remote server. This requires that an Oracle instance is
installed on the remote server to recover the database from these

V. Use RMAN to rig a standby database, instead of using DataGuard or
GoldenGate. This involves another Oracle instance running on the
remote server, use of RMAN to clone the primary database, shipping
primary database RMAN backup files to a remote server and, finally,
running an RMAN recovery of the database on the remote server.

VI. Create an Oracle RAC 2-node cluster with one cluster being on a
remote server. I believe that this is possible with even Oracle 11.2
Standard Edition, possibly with a relatively small license charge per

I recommended option “III” because it would not require another instance of Oracle on the remote server and it would not slow down the log writer Oracle process (LGWR) which would most likely result in a general database slowdown. In addition, the server OS/network resources used, if the script is not run very excessively, should not be sufficient to slowdown the Oracle database or the application. My suggestion is to determine the average amount of time that the database takes to fully archive a log, decide how many logs you would like copied at the same time and use that average as a guideline to determine how frequently to schedule the script.