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Appeared on: Wednesday, February 23, 2005
SONY BW-RU101 PDD


1. Introduction

SONY BW-RU101 PDD - Page 1

- Introduction

There has been an increased need for more storage capacity over the last few years, where we have seen hard disks for example, progress from a meagre 2GB to over 250GB in less than a decade. This need has also overflowed into the world of DVD recording, which has very quickly evolved from single layer (4.7GB), to double layer recording (8.5GB) and now onto the more recently introduced blue-laser technologies of the Blu-Ray and HD-DVD recording formats, which promise even higher storage capacities, up to 25~30GB and more. Blue-laser technology is already available and more specifically, from SONY with their BW-RU101 drive where users can store up to 23.3GB of data on a single layer disc. In this review, we present SONY's PDD (ProData) format and we examine the performance of the drive under real life tests.

- The Format

Sony is among the first companies to use blue-laser technology on an optical storage drive. The format was announced back in August of 2003, with the main feature of providing 23.3GB of storage capacity on just one single-sided media and with data transfer rates as high as 11 MB/sec!

Sony's blue laser technology roadmap, extends three generations, with the aim of doubling capacity and performance from one generation to the next.

The second generation technology is expected to feature 50GB product capacity on a single sided double layer disc with a transfer rate of 18 MB/sec (144 Mbps) to be available around end of 2005, and a 100GB product (multi-layer media and improvements in encoding and/or signal processing) with a transfer rate of 36 MB/sec (288 Mbps), currently planned for release by 2007.

Despite the fact that blue lasers are being used, the format is NOT Blu-ray or compatible with Blu-ray. SONY has developed the PDD format for professional applications and transfer rates higher than the Blu-ray Disc technology can accommodate. SONY's PDD format hasn't achieved any format standardization from ECMA, ISO or any other format standardization organization. The format uses Reed-Solomon error correction with error rates less than 10^-21, while MO drives have an error rate of 10^-12.

Sony’s new drive and media cartridge are designed to be impervious to dust and other air-born contaminants, resulting in ultimate reliability and durability. As SONY describes "...After the media is inserted into the drive, the front shutter closes completely and the airtight structure of the drive prevents dust particles from getting in contact with the drive mechanism, optical pickup, and media surface. Plus, an internal automatic lens cleaning feature enhances the effect of dust protection. The media itself offers further advantages such as an anti-static cartridge and hard coating media surface protection..."

SONY claims that the data integrity rating of the media is more than 30 years for both the rewritable and write-once formats. Sony's blue laser recording technology allows higher density recording onto a 120mm disc than current optical MO, CD and DVD discs that use red laser technology.


2. Blue laser technology

SONY BW-RU101 PDD - Page 2

According to SONY, the following technological advancements facilitate the achievement of higher-capacity and higher-density:

  1. Narrowing the size of the laser beam wavelength by using a 405nm wavelength blue laser.
  2. Increasing the NA (Numerical aperture, determines the minimum resolving power of a lens for writing and reading) of the objective lens to 0.85 to minimize the beam spot range.
  3. Adopting a very thin cover layer, 0.1mm thick to prevent any disc tilt for maximum read/write reliability.
  4. Narrowing tracking pitch size to 0.32µm to heighten the recording density.

Blue laser and 0.85 NA lens enable high-density recording

By reducing the wavelength of the laser beam from red to violet, it is possible to make a narrower “beam spot”, thus enabling higher recording densities. “Professional Disc for DATA” employs a blue laser with a wavelength of just 405nm, enabling a data density some 2.6 times greater than that of the red laser technology used for conventional optical media. Moreover, the lens (used for focusing the laser beam) has a numerical aperture of 0.85 — greater than that used for DVDs (NA: 0.6) and MO discs (NA: 0.575). The resulting narrow beam further doubles recording density. As a result, track pitch is just 0.32µm, making it possible to record as much as 23GB on one side of a disc. Below we can see a comparison between DVD and SONY's PDD technology:


(Courtesy of SONY)

0.1mm cover layer enables high tilt tolerance

The overall thickness of the 120mm disc is 1.2mm, the same as that of a DVD disc. However, the recording layer has a cover layer of just 0.1mm thickness. This effectively increases the margin of error when the disc tilts or bends. Tilt tolerance is thus significantly higher than that of conventional optical discs, enhancing reliability for read/write operations. Below we can see a comparison between DVD and SONY's PDD technology:


(Courtesy of SONY)

Higher Performance

Compared to MO and DVD-RW, “Professional Disc for DATA” offers higher performance, at least according to SONY. Capacity is approximately 3 times that of MO and 5 times that of DVD-RW, maximum write speed is 2 times that of DVD-RW (4x) and 1.5 times that of MO. Below we can see a comparison chart between DVD, MO and SONY's PDD format:


(Courtesy of SONY)


3. Design

SONY BW-RU101 PDD - Page 3

- Design of the Drive

Dustproof design

As we all know, dust is the principal enemy of optical discs. This is why the BW-F101 internal drive has been designed to be completely airtight; dust is prevented from entering the case via either the mounting screw holes or the space between the top and bottom covers.


(Courtesy of SONY)

The main entry point for dust is the shutter, but a dual-shutter mechanism has been adopted to ensure an airtight enclosure even with the media inside the drive. In addition, this drive is maintenance-free: an internal brush mechanism ensures periodic, automatic cleaning of the pickup lens to achieve the highest level of reliability.

Automatic CAV/CLV selection

“Professional Disc for DATA” drives support both CAV (constant angular velocity) and CLV (constant linear velocity) transfer modes when reading and writing data. In CAV mode the disc rotates at a constant speed, meaning that the transfer rate slows as the pickup approaches the center of the disc, but seek operations are fast (110ms average). In CLV mode the speed of the pickup is constant, so although seek operations take longer, the maximum transfer rate of 11MB/s is maintained at all times. The drive firmware automatically selects the Optimum mode to ensure the best overall performance. For example, if accessing a series of relatively small text files, CAV is used for fast seek times, but when reading large music or video files, CLV is employed to ensure the maximum transfer rate. The factory setting ensures that the drive automatically selects the optimum transfer mode. But if necessary the user can select the transfer mode: DIP switches allow selection of either CAV or Optimum mode, while any one of the three modes (CAV, CLV or Optimum) can be specified by a mode select command.


(Courtesy of SONY)

High-capacity cache

The drive is equipped with a 16MB cache, much larger than the 2MB cache of DVD-RW drives or even the 8MB cache of MO drives. This effectively reduces the load on the CPU when writing to the disc and improves performance when accessing data, thanks to its enhanced capacity to read ahead. Error recovery is also improved: the large cache minimizes any impact on performance.

Low power consumption

When there is no disc access for a certain length of time, the drive starts shutting down components and circuits to save power. This follows a phased schedule (see table below) that parks the optical pickup (OP), engages idle mode, cuts spindle power and eventually switches off the cooling fan. Power consumption is cut by approximately 50%, but there is more to it than that: in fan-off mode the drive produces less heat and attracts less dust since there are no moving parts. The duration of each phase in the sleep sequence can be adjusted using mode select commands to tailor performance for different applications.


(Courtesy of SONY)


4. Specifications

SONY BW-RU101 PDD - Page 4

- Drive Specifications

Model name
BW-S101/RS101
BW-U101/RU101
Drive Type
External type
Disc Type
Rewritable (PDDRW23B), Write-once (PDDWO23B)
Interface
Ultra 160 LVD/SE SCSI
USB2.0
Capacity (Online)
23.3 GB
Data Transfer Rate Sustained Read
11 MB/s (CLV), 4.5 - 11 MB/s (CAV)
Sustained Write
9 MB/s* (CLV), 4.5 - 9 MB/s* (CAV)
Burst
160 MB/s
(synchronous) (max)
480 Mbps (max)
Logical Sector Size
2,048 bytes*
Seek Time (CAV) Full Seek
200 ms
1/3 Seek
110 ms
Load/Eject Time
6.0 sec / 3.5 sec
Buffer Memory
16 MB
MSBF
300,000 SWAP
MTBF
100,000 hours
Dimensions
199.3 (W) x 59 (H) x 306.3 (D) mm
Mass
4.5 kg
Power Supply
AC 100-240V +/- 10%, 50/60Hz +/- 5%
Power Consumption
30 W (average)
Calorific Power
34.4 kcal/h (average)
Operating Temperature
5 - 40°C
Operating Humidity
10 - 90% (non-condensing)
Storage Temperature
-30 - 60°C
Storage Humidity
5 - 90% (non-condensing)
Mount Position
Horizontal/Vertical
* Verification of write operations (factory setting) decreases max. transfer rate.
**512-byte sector size can be chosen by using mode select command.

5. The media

SONY BW-RU101 PDD - Page 5

- The media

Designed to protect mission-critical data

The antistatic cartridge is designed to withstand both heat and shock. Furthermore, the robust cartridge has a revolving shutter mechanism to prevent the entry of dust. As a result both types offer a data integrity rating of more than 50 years.

Dual-head compatibility

The shutter has been specially designed to allow for multiple-pickup mechanisms in future iterations, thus enabling a smooth transition to drives offering far higher read/write speeds.

Rewritable and write-once media

Two types of single-sided media are available, rewritable and write-once, both offering 23GB of storage capacity. Rewritable media allows data to be rewritten and overwritten repeatedly. Write-once media cannot be reformatted and does not allow data to be overwritten, making it ideal for long-term archiving; as long as there is space available, data can always be added but never altered or delete

Model name
PDDRW23B
PDDWO23B
Format
Rewritable
Write-once
Capacity
23.3 GB
Sector Size
2,048 bytes*
Recording Layer
Phase change
Track Pitch
0.32 µm
Cover Layer Thickness
0.1 mm
Disc Diameter
120 mm
Cartridge Dimensions
128.6 (W) x 130.6 (H) x 9.1 (D) mm
Erase/Write Cycles
> 10,000 times**
Mass
90 g
Estimated Shelf Life
> 50 years**
Estimated Archival Life
> 50 years**


6. Installation - Page 1

SONY BW-RU101 PDD - Page 6

- Installation/Package

We received at our labs, the external USB2.0 version with the codename BW-RU101. There's no retail package to speak of, just the bare drive along with power cable, USB2.0 connection cable, a printed manual in 5 languages and a CD with corresponding software. In addition, SONY sent use four (4) PDD media , 2 recordable (PDDW23B) and 2 re-writable (PDDRW23B). The drive can be found with an attached price tag of $2500~$3000, while the media is available for $45. The drive is available in three models, internal (BW-F101), external USB2.0 (BW-RU101) and external SCSI (BW-RS101). A 19-inch rack-mount auto changer is available that provides up to 1.56TB storage capacities.


The drive's design is attractive to the eye, due to the blue drop down bezel. The front is rather simple with the Sony, PDD Data and 23GB logos. Also on the front panel are the power led, activity led (green when idle, orange when reading/writing), eject button and emergency eject hole which has a protective rubber cover.

On the back of the drive, we can find the function switches (mainly used to force CAV mode), the power connector, the on/off switch and the USB2.0 connection interface. As we stated during the introduction, the drive includes a rotation fan and a special internal air cooling system that prevents dust from entering inside the drive.

Below we can see the various modes that can be activated with the available switches:


7. Installation - Page 2

SONY BW-RU101 PDD - Page 7

Installation was fairly straightforward, simply plug-in the power and USB 2.0 cables and then switch on the drive. The drive was recognized by Windows XP as a mass storage device on our PC, with device id BW-F101 ID:

Looking at the system properties, the drive was listed under Disk Drives and not under DVD/CD-ROM drives:

You can set the write caching mode, quick removal or performance, according to your needs from the properties dialog window:

The drive's installed firmware was 1.19, the latest available. SONY offers free firmware upgrades with a password/login process:

The SONY PDD drive is compatible with computers running Windows 2000/XP (FAT32 or NTFS), Windows Server 2003 (NTFS), Mac OS10.x (HFS) and certain varieties of UNIX, including Linux, without installing any special drivers. Information on drivers and software is available from this link. For Windows, the disc drive utility is provided as bundled software for external drives BW-RS101 and BW-RU101.

Before being able to use a disc, the user should carry out a physical format of the disc. This will check the integrity of the disc and relocate bad sectors if present. This can be performed in one of two ways:

The first is available through Sony's Physical Format utility:


8. Software

SONY BW-RU101 PDD - Page 8

The second is with the included Disk Drive Tune Up software from Software Architects. Once the physical format has finished, the user can then use the disk. Note that the drive by default performs formatting in the foreground which takes around 80mins to complete. The drive can also be set to perform background formatting (function switch settings), whereby formatting is initiated automatically without an explicit format command from the user, and is carried out in the background. It is possible to read and write on the disc while background formatting is being carried out but the format process will take at the very least, 135 minutes.

The Disk Drive Tune Up software is a very useful suite since you can perform a series of actions, including creating partitions and formatting a disc for FAT16, FAT32 and various UDF builds:

The software supports UDF 1.02, 1.50, 2.00 and 2.01 versions. It is advisable for users to use the latest UDF 2.01 which supports 4K clusters under Win2000/XP systems:

We can also create partitions, again a fairly easy procedure. This is especially useful when the FAT16 format type has been selected where the partition size limit is 4GB (see snapshot above).

Under the Test option, the user can test the integrity of a disc either with the read/verify or write/verify process. The software will report any ECC problems found:

The necessary OS format can be done either with Windows Format or with the Disk Drive Tune Up software:

The formatted disc had 20.5GB free space:


9. Tests

SONY BW-RU101 PDD - Page 9

- Testing

For testing the Sony BW-RU101, we used WinBench 99 and HD Tach 3.0.1.0 benchmarking software, mostly with PDDRW media. First, lets see the CLV and CAV reading modes. WinBench 99 showed that the reading performance of the PDDRW23 was around 11MB/sec, CLV reading mode confirmed:

Click To Enlarge!

When forced into CAV reading/writing (switch 2 at 1 position), the drive started reading at 4.8MB/sec and ends at 11MB/sec, full CAV reading for the BW-RU101 as per the specs:

Click To Enlarge!

Then we fired up, HD Tach 3.0.1.0. The software can perform three types of reading tests:

as well as the corresponding writing modes:

Below we can see the table with all the test results for the CLV/CAV modes:

Full
Average Reading (Mb/sec)
10.7
8.0
Average Writing (Mb/sec)
4.2
3.2
Random Access (ms)
197.6
199.4

The results from HD Tach are interesting. Again, the superb reading performance of the BW-RU101 was confirmed, 10.7MB/sec for CLV and 8.0MB/sec for CAV reading modes. However, what wasn't confirmed was the writing performance. Sony promises up to 9MB/sec, which however, didn't show up in our test results. After reading the drive manual again, was noticed something interesting:

"...Inhibit Verify: Using a physical formatted disc, is highly recommended if you inhibit verify for writes. Although disable verify for writes quickens the write transfer rate, it may reduce the reliability of written data. Even if you inhibit verify for writes, if the disc is not physical formatted, the drive forces verify for all write operations..."

What this means is that if the "Inhibit Verify" switch is off, every write operation will be accompanied by a verify. This is probably why the writing speed was half of what is given in the specifications. This is very similar to what occurs with DVD-RAM media. So we enabled "Inhibit Verify", but again the writing performance was more or less as before.


10. Conclusion

SONY BW-RU101 PDD - Page 10

- Conclusion

Sony's BW-RU101 is probably among the first optical storage drives (along with Plasmon's UDO) that use blue-laser technology to reach storage capacities of 23GB with Sony promising up to 100GB storage by the end of 2007. The drive uses cartridges that offer additional safety mechanisms against dust and will keep your data safe. The RW and write once discs have the same capacity (23GB) and more or less the same price.

The drive itself includes interesting technologies and probably from the PDD white paper we expected to see very high reading/writing speeds, since Sony promises up to 11MB/sec reading/writing with both PDDR/RW media. The test results confirmed the drive's very good reading performance, especially with the CLV mode. The writing performance however was half that specified. We believe this may be due to the verify after write feature, which of course boosts data integrity and prevents data loss. The access times was more or less the same for both CAV/CLV modes, at least with PDDRW media.

At a retail price of $2500~$3.000, the BW-RU101 doesn't come cheap, but then again it is aimed at the professional market and not for home use. Media costs around $45, where the cost per Gigabyte is $0.51. Similar capacities can be found for much less (tape is $0.20) but of course tape doesn't offer the data safe mechanisms and the access times of an optical storage device. With the drive aimed at professional use, home users are awaiting with great expectations upcoming blue laser drives from both the HD-DVD and Blu-Ray Alliances.

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