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Appeared on: Wednesday, June 16, 2004
Plasmon UDO30I external SCSI Drive

1. Introduction

Plasmon UDO30I external SCSI Drive - Page 1


Plasmon announced back in November of 2003, the UDO technology as a new standard for professional optical storage, aimed at both large and small companies looking for an easy archival storage system. Based on ultra density, phase change blue laser technology, it is the recognized successor to 5.25 inch MO (Magneto Optical) storage and is available in both Rewritable and true Write Once media formats. Our review has the goal of introducing UDO technology, and to trial how it works.

- UDO Technological Background

Plasmon`s UDO drive is one of the first blue-violet laser and phase change products available on the market, offering the next generation of professional optical storage devices. UDO uses non contact recording to provide robust and reliable performance. Blu-Ray and PDD (Professional Disc for DATA from SONY) lasers use 0.85 numerical aperture (NA), while UDO lens has 0.7 NA for higher reliability and 0.1 mm cover layer for disc protection. The opto-mechanical assembly for the UDO drive comes from Asahi Pentax, a leading manufacturer of opto-mechanical assembly for 5.25" opto-mechanical drives.

- Why would someone need UDO Technology?

According to Plasmon, archival storage solutions are important for all organizations, large and small, everywhere round the world. The following changes in business practices and government oversight make an archival storage strategy essential:

Authenticity and Trustworthiness

UDO provides absolute data authenticity for regulatory compliance or for any application where archived information must remain 100% unchanged. UDO’s patented Phase Change recording process permanently alters the molecular structure of true Write Once media, ensuring data integrity at the most fundamental level.

Long-term Data Retention

UDO has been designed to provide decades of dependable data retention. A highly stable recording surface delivers media life in excess of 50 years, minimizing the frequency of data migration and virtually eliminating media maintenance.

High Capacity and Scalability

Rapidly growing archive data volumes demand solutions with high initial capacity and flexibility to scale over time. Blue laser technology gives 30GB UDO a three-fold increase in storage capacity compared to previous generation MO (Magneto Optical) and DVD technologies. The removability of UDO cartridges, combined with the on-line media management capabilities of optical storage libraries, means scalability is essentially unlimited.

Rapid Information Access

Knowledge assets are useless if they cannot be accessed when needed. UDO has fast 25-millisecond random access capability, facilitating timely retrieval of relevant data.

Low Total Cost of Ownership

UDO has a highly competitive archival storage TCO. With attractively priced 30GB media, the acquisition cost of a UDO library compares favorably with much less reliable tape or DVD solutions and costs a fraction of hard disk-based systems. UDO’s ISO standard 5.25 inch media cartridge, which permits the use of MO and UDO media in the same library, eliminating the necessity for migration from 9.1 MO media. Planned introductions of backward-compatible 60GB and 120GB UDO drives guarantee investment protection and minimize future migration expense.

- Media Specifications

The drive uses Plasmon 5.25 inch double sided UDO media cartridges with 30 GByte capacity. These are available in both true write once and rewritable media types. They use the same form factor as MO (Magneto Optical) media but are not compatible with MO drives, nor are MO media compatible with UDO drives. New UDO media must be formatted before being used, and behave like Removable/Floppy disk drive.

Disk Diameter
130 mm
Disk Thickness
2.4 mm
Cartridge Size
5.25 inch - ISO Standard 135x153x11mm
30 GB
Sector size
8 KB
Number of user sectors/side
Data area
27.0-62.5 mm
Recording layer
Phase change
Recording format
Land & Groove
Recording side
Both sides
Recording density
7.4 Gb/in
Media layers
Data encoding
RLL (1,7)
Rewrite cycles (Rewritable Media)
Media life
50+ years
Archival Temperature
Archival relative humidity

The media cartridges, physically identical to 5.25" MO, provide compatibility with current library automation systems but as we said before, backwards compatibility is not available with current MO technology. UDO`s media supports both true WORM (Write Once Read Many) and rewritable (RW) media types thanks to phase change recording technology while providing 50 years of data life. For 30 GB UDO-R media the cost is $60 which should decrease to $15 by the release of the third generation products, according to the company.

Generation 1
Generation 2
Generation 3
30 GB
60 GB
120 GB
Transfer Rate
up to 8 MB/s
up to 12 MB/s
up to 18 MB/s
2000 RPM
3000 RPM
3600 RPM
Avg Seek Time
25 msec
25 msec
25 msec
Numerical Aperture
Media Layers
Sector Size
8 KB
8 KB
8 KB
SCSI Transfer Rate
80 MB/s
80 MB/s
80 MB/s
Load Time
5 sec
5 sec
5 sec
Unload Time
3 sec
3 sec
3 sec

2. The Drive

Plasmon UDO30I external SCSI Drive - Page 2

The Drive

The device comes with UDO drive resource CD, 68pin Micro-D wide SCSI cable, a SCSI terminator, power cable and two 30 GB UDO media, one rewritable and one write once read many (WORM).

On the front of the drive, there are from left to right, the UDO logo, the emergency eject hole and the eject button. Above it there are two leds, the left one is the active (Amber) and the right one is the ready (Green).

On the back of the drive from left to right there is the power switch below of the SCSI ID switch, two SCSI-III 68-pin Micro-D connectors above the AC power connector and the fan/air filter.

The Plasmon UDO30I SCSI drive features double sided 30GByte (15GB per side) storage on rewritable and write once media. It uses half height 5.25 inch form factor media cartridges, operating at Constant Angular Velocity (CAV) with continuous spin at the higher rate and communicate through a SCSI III connection.


External Wide Ultra 2 LVD SCSI keyed 68 pin micro-D

Performance Rotational Speed: 2160 rpm
Media load time: 5 sec
Media unload time: 3 sec

Avg. seek time (1/3 full stroke): 35 ms

Max. Read Transfer Rate: 8 MB/s

Max. Write Transfer Rate: 4 MB/s (including verify)


Error Correction: Reed-Solomon

Objective Lens Numerical Aperture: 0.7 NA
Laser Wavelength: 405 nm
Reliability MSBF: 750,000 load/unload cycles
MTBF: 100,000 hours
Operating Conditions Operating Temperature: 5 to 45C
Operating Humidity: 5 to 90% RH (non-condensing)
Drive Orientation: Horizontal or Vertical
Maximum SCSI transfer rate

40 MB/s

Buffer memory 32 MB
Dimensions&Weight H 41.1 x W 146 x D 203 mm - 1.5 kg

- Installation

When the device was connected to our PC, it was identified as Disk drive "Plasmon UDO1 SCSI Optical Device" under WinXP. It is necessary first to install a hotfix patch prior to inserting the media into the drive. This step is needed because the UDO drive uses 8KB sector size for optimized read/write performance across a wide range of file sizes, which Windows does not support, even with Windows XP SP1.

The patch is supplied on the UDO drive resource CD. Next, we installed the Software Architects UDO driver Software, also on the resource CD.

Also, under drive properties, write mode tab, we selected cached write mode for increased performance, although direct write mode is the safe choice should the PC lose power or crash.

For our tests we are going to use only the RW cartridge as the Write once media unfortunately for us, was defective and the system did not recognize it.

3. Reading Tests

Plasmon UDO30I external SCSI Drive - Page 3

Reading Tests

Using the RW cartridge, the UDO30I operates like a Removable/Floppy device using UDFS format with a 5.25" cardridge. Blank media requires a quick format before use. For the test we copied 6,129 different files, large and small, from the RW cartridge using drag & drop, to our hard disk drive. The reading time is listed below while the total bytes was 13.6 GB.

Drive Action

The sequential read test was achieved with the SCSI Mechanic 3.0 utility with the RW cartridge full of different types of files. We let the test run for 30 min. in order to obtain more accurate results.


Average read transfer rate is 6.45MB/s and the maximum is 8.57MB/s.

Using AnalyzeDisk's IPEAK utility from Intel, we measured the average access time needed when reading from the drive.

The Distribution of Read Service Times test uses a large number of samples, 25,000 to be exact, and measures the time taken for random single sector read requests across the entire drive's surface.

The average access time is 61.7 ms

Random reads gave us what can be considered high access times for read access at 61.7ms when compared to a hard disk for example.

4. Writing Tests

Plasmon UDO30I external SCSI Drive - Page 4

Writing Tests

The write test involves copying 6,129 different large and small files to the RW cartridge using drag & drop and measuring the time taken. The time for writing is listed below while the total bytes transfered was 13.6 GB.

Drive Action

Sequential write test carried out again with SCSI Mechanic 3.0 and the RW cartridge full of different kinds of files. The test needed 30 minutes.

Average write transfer rate is 9.8MB/s with a maximum transfer rate of 24MB/s.

To measure the average access time needed when writing to the drive we again used AnalyzeDisk.

The Distribution of Write Service Times test, takes 25,000 random single-sector writes and measures the average access time it takes to writes across the entire drive's surface.

The average access time is 87.65 ms

Write access time of 87.65ms is far higher than the company's specifications.

5. Conclusion

Plasmon UDO30I external SCSI Drive - Page 5




  • High capacity removable disks (30 GB)
  • With RW Media operates like a Removable/Floppy device
  • Price
  • Low read/write speed performance
  • OS drivers needs improvement

UDO uses its own phase change recording process, offering one of the most robust storage methods and ensuring data integrity at the most fundamental level. Target markets for UDO technology include banking, telecoms, insurance e.t.c where the need for high reliability in storage is high (our tests could not confirm whether this device is indeed highly reliable, since that would only show up with long term useage/testing).

The results reflect low overall performance with the drive. SCSI Mechanic 3 gave us sequential read transfer of about 6.45MB/s and 9.8MB/s write transfer. Analyze Disk measured average read access time of 61.7ms and average write access time of 87.65ms placing the drive in the low performance devices category.

When copying, to keep performance high, the manufacturerer recommends copying up to 1000 to 1200 files per directory at a time. Also, the user must be sure that there are no other UDF (DVD) file systems installed as they interfere with the UDO driver software.

Desktop UDO drives are priced at approximately $3,200 USD. The price is rather high for end users, but Plasmon is aiming at the Proffesional market, where reliability is important.



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