A real quick post today, as I was reviewing some of our DataDomain statistics. Below shows the deduplication information for an Oracle database file (~16gb) that was backedup via RMAN to our DataDomain via NFS mount point.
DD01# filesys show compression /backup/db/xxx/xxx/xx6e_1_1
Total files: 1; bytes/storage_used: 59.1
Original Bytes: 16,252,249,684
Globally Compressed: 954,839,915
Locally Compressed: 272,055,847
bytes/storage_used: 59.1 = Compression and Deduplication ratio
Globally Compressed Factor = Pre-Comp / (Size after de-dupe)
Locally Compressed Factor = (Size after de-dupe) / Post-Comp
From above you should be getting an idea of the deduplication, but lets follow DataDomain’s formula
Reduction % = ((Pre-Comp – Post-Comp) / Pre-Comp) * 100
Now put in values from our above example
16,252,249,684 – 272,055,847 / 16,252,249,684 * 100 = 98.326%
That gives us a 98.326% reduction!
Basically what I am trying to say is that if you are not doing some sort of deduplication + compression on your Oracle backups, you should look into it.
Note(s): The above information is from a system running Data Domain OS 126.96.36.199-175623. Also, remember that deduplication savings grow as the same types of blocks are written. This system has been in production for over a year. We have about 1tb raw of Oracle data being written to the DataDomain which helps the dedupe ratio.