DVD-RAM writing performance:

The Plextor PX-B900A supports writing and reading the DVD-RAM format. Lets us look at the recording side of the disc, and as you can see it has differences from the other DVD+R/W/R9 DL and DVD-R/W discs.

We can see a very fascinating pattern of darker spots. These tick marks are "address information" ("Pre-mastered Pit Header Field") which are embedded onto the disc. This is header information in front of data sector area, and is the same format as HDD and MO.

A DVD-RAM’s disc can be formatted in the following formats:

• FAT32
• UDF 1.02
• UDF 1.50
• UDF 2.00
• UDF 2.01
• UDF 2.50

By formatting a DVD-RAM disc with FAT32 it will act like a removable hard drive and all writing will be done as “background processes”. Meaning you do not have to wait for it to finish, you can start or work with other applications while the DVD-RAM is working without noticing any “hangs” or CPU slowdowns.

Lets us take a look at the media we are going to use in these tests:

Verbatim 5x media manufactured by Matsushita

Now let’s see how DVD-RAM media is written and read by the Plextor PX-B900A:

Verbatim 5x without verification

Verbatim 5x with verification

For those of you who are not familiar with DVD-RAM, you may probably think that something went wrong during the write process with the verification turned on, since the 5x media was written at 2x. But not to worry, that is pretty normal for DVD-RAM discs, the reason for the “low” speed is, the drive constantly reads back the data after writing it to verify that it’s written correctly. We can also call it a “bullet proof” writing/verify technique, with no data loss/errors.

DVD-RAM has error correction, but also has error replacement to spare sectors as a "defect management" function. This gives higher reliability than other DVD format.

Another advantage with DVD-RAM is that the discs can be formatted/erased/written at over 100.000 times before it will/can cause/report any errors. Let’s try to read back the disc that we wrote:

As we can see, the Plextor PX-B900A use a CLV reading method, and reads the disc at its rated write speed, meaning our 5x media was read at 5x.

Head on to next page and read about the most interesting part: Blu-ray features and performance...

DVD±R DL Writing performance

Blu-ray (BD-R) Writing performance