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Appeared on: Wednesday, October 26, 2005
Plasmon UDO30D-SE

1. Introduction

While there has been a lot of talk over the past year or so about the next generation of optical disc storage formats, with the Blue-ray and HD-DVD camps battling it out to see who will prevail, one company has been actively using the technology to provide reliable, professional archival storage solutions. That company is Plasmon.

Founded in 1984, Plasmon is a pioneer in optical storage technology and has emerged as a leader in the archival storage industry. Plasmon develops and manufactures UDO (Ultra Density Optical) professional 5.25 inch optical drives and media, specifically designed to meet the secure archival storage demands of among others, corporations and government agencies. The media longevity and data authenticity of the blue laser UDO technology makes it ideally suited for environments subject to regulations on data retention and the legal admissibility of electronic records.

UDO Technological Background

Plasmon`s UDO drive was 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 a numerical aperture (NA) of 0.85, while UDO lens has 0.7 NA for higher reliability and a 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 assemblies for 5.25" opto-mechanical drives.

The blue laser recording technology of UDO also achieves far greater data densities, resulting in dramatically higher media capacities. First generation UDO media has a capacity of 30GB, with a roadmap extending to 60GB and 120GB in future generations. UDO delivers all the traditional strengths expected from optical storage such as record authenticity and media longevity, but at a much higher capacity and lower cost than previous generation products. Plasmon's Archival Storage Total Cost of Ownership Analysis provides a detailed explanation and quantifies the acquisition and operating costs of different storage technologies used for archiving data, including UDO.

UDO media is available in Write Once (True Write Once and Compliant Write Once) and Rewritable media formats. Each of the three media types has its own physical and operational properties making it well suited for different service levels within an overall archive strategy. Since UDO drives and Plasmon optical libraries support all media types, organizations can match the media format with the specific demands of each document class.

Plasmon UDO Products

Plasmon provides a series of products using the UDO technology, ranging in scale from archival storage strategies for corporations, down to small office environments.

The G-Series libraries are used in archive applications that include, Electronic Content Management (ECM), Document Imaging, Hierarchical Storage Management (HSM), and Information Lifecycle Management (ILM). They are the backbone of the archival storage strategy for corporations and government agencies worldwide. There is also a G-Series for the IBM OS/400, which is supported natively within the IBM OS/400 and i5/OS operating systems. These libraries are automatically identified by OS/400 and i5/OS, presenting the library as a standard storage device.

At the other end of the scale, there are the UDO internal and desktop drives. The Desktop Drive brings professional archival storage to small office and departmental environments at an affordable price. There is also the option of future expansion to G-Series library configurations when archive capacity grows.

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. For a full analysis, read the article Archival Storage Total Cost of Ownership Analysis from Plasmon.

UDO Desktop Drive Specifications Summary

Media Load Time 5 sec typical
Media Unload Time 3 sec typical
Average Seek Time 28 msec
Drive Buffer 32MB
Max Sustained Transfer Rate - Read 8 MB/s
Max Sustained Transfer Rate - Write 4 MB/s (with verification)
Max SCSI Transfer Rate 40 MB/s
MSBF - Mean Swap Between Failure 750,000 load/unload cycles
MTBF - Mean Time Between Failure 100,000 hours
Interface Wide Ultra 2 LVD SCSI

- UDO Media

As was stated earlier, UDO media is available in Write Once (True Write Once and Compliant Write Once) and Rewritable media formats. Rewritable UDO media is typically used in archive applications where the stability and longevity of optical media are important, but records change frequently and there is a need to delete and rewrite information. UDO Rewritable media is ideal for small office and departmental applications or in larger unstructured archives that are not subject to specific regulatory or corporate standards.

True Write Once media offers the highest level of physical record authenticity and is ideal for document classes with very long or indefinite record retention periods. Common uses of True Write Once media include medical, financial, industrial and cultural applications that require documents be retained for years or decades and must be held to a very high standard of legal admissibility.

Compliant Write Once media combines longevity and secure authenticity of True Write Once UDO media with the ability to shred expired records for document classes that demand physical disposal. Designed specifically to assist organizations in meeting regulations on data retention and disposition while managing corporate risk, Compliant Write Once media can be used in a wide range of financial, administration and legal applications.

UDO media uses a patented and field-proven Phase Change recording technology that produces a very stable recording surface with a media life in excess of 50 years. Since it is a non-contact, non-magnetic recording process, data written on UDO media does not degrade with use, tolerates a wide range of temperature and humidity conditions and is insensitive to magnetic field exposure.

In order to protect UDO media from physical damage and contamination (dust, fingerprints, etc.), the disk is enclosed in a rugged ISO standard 5.25 inch cartridge. A unique double-shutter design prevents dust accumulation on the top surface of the media during recording. Lower dust contamination means more reliable read and write operations and extended media life.

UDO media has been certified by ISO, IEC and Ecma International. Plasmon manufactures UDO media in the United Kingdom and has granted a license to Mitsubishi Kagaku Media (MKM) for manufacturing second-source media in Japan. MKM's media products are sold under the Verbatim brand in North America, Europe and Asia and the Mitsubishi brand in Japan.

- Media Specifications

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


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. Test Methodology

The UDO Desktop Drives comes as either an internal drive or an external drive with a SCSI interface connection. The unit we received from Plasmon was an external drive with the Wide Ultra 2 LVD SCSI interface. In the photos below, we see the 68pin Wide Ultra SCSI plug, SCSI interface connections located on the rear of the UDO Desktop drive along with the SCSI terminator, and finally the SCSI cable.

Plasmon recommends the use of the Adaptec 29160 SCSI interface controller. The Adaptec 29160 SCSI interface card is a single channel, 64 bit controller with 160 MByte/sec throughput. It is a PCI card that can accommodate both internal and external Ultra160 SCSI (LVD) devices.

Click to enlarge

We installed a 29160 SCSI card in our test PC and downloaded and installed the latest drivers from Adaptec's site. We then turned off our PC before installing the UDO Desktop driver and connecting the UDO Desktop Drive.

There are a number of drivers available for the UDO Desktop Drive, catering for the various *nix and Windows versions. The full driver list includes Plasmon's UDO Desktop Driver, which was included on the CD with our drive, and the Diamond Storage Management Software also from Plasmon. The remaining drivers are from ISVs and provide support for various file systems for the *nix and Windows operating systems.

The Plasmon UDO Desktop driver provides support for the UDF and AFS file systems under Linux, WinXP, Windows 2000 and Windows 2003. The Diamond Storage Management software provides support for the UDF, AFS and PFS file systems. The Diamond Management Software is intended for Plasmon's G-Series and D-Series libraries where the library is transformed into a virtual hard drive available to users via a drive letter or network share. There is also a feature-rich API (Application Program Interface) so that developers can integrate optical storage capabilities into their applications. Example applications include document management, records and image archival for medical imaging/PACS, finance, banking, insurance claims processing, call centre voice recording, and email archival storage. For full details of the Diamond Storage Management software, visit the Plasmon web site.

Before proceeding, we will provide a brief description of the different file systems referred to above. You can also view the document "File System Performance Considerations" provided by Plasmon.

We chose to use the UDF format for our tests. By right clicking with the mouse on the UDO drive icon in Windows Explorer, the following menu appears:

The main options available for the UDO drive are Eject, Rename, Format and Change Drive Letter. The purpose of each option should be obvious. Before using any media, you need to format it. There are two types of media available, RW and WORM. We inserted the RW media supplied to us by Plasmon and proceeded to format it.

With our media in the drive and formatted, we were ready to start testing the unit. Before proceeding to describe the test procedures, it is important to mention that the primary purpose and use for which the UDO drive is intended, is as a backup and archiving device. As such, the primary concern is not so much speed, as reliability and integrity, especially over time. The document entitled "Optical Media Life Prediction Methodology" from Plasmon Data Systems describes lifetime prediction for optical media.

In order to test the UDO Desktop Drive, we used IOMeter.

Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It measures performance under a controlled load. Iometer was formerly known as "Galileo". It was originally developed by the Intel Corporation and was later given to the Open Source Development Lab (OSDL).

Iometer is both a workload generator (that is, it performs I/O operations in order to stress the system) and a measurement tool (that is, it examines and records the performance of its I/O operations and their impact on the system). It can be configured to emulate the disk or network I/O load of any program or benchmark, or can be used to generate entirely synthetic I/O loads. It can generate and measure loads on single or multiple (networked) systems.

Iometer can be used for measurement and characterization of:

Taken from the IOMeter User Guide

We used a commonly available, example access pattern that closely simulates a network server's file access load. The table below describes this access pattern. The second column specifies the range of file sizes, from 512 bytes up to 64k bytes. The respective access for each file size is given in the first column as a percentage. For example, for a 4kB file, we have 60% access which means that 60% of accesses to the server are for files with a size of 4kB, while only 10% are for files of size 64kB. Of those accesses on 4kB files, 80% are reads and 20% will be writes (third column).

File Server Access Pattern (as defined by Intel)
% of Access Specification Transfer Size Request % Reads % Random
10% 0.5 KB 80% 100%
5% 1 KB 80% 100%
5% 2 KB 80% 100%
60% 4 KB 80% 100%
2% 8 KB 80% 100%
4% 16 KB 80% 100%
4% 32 KB 80% 100%
10% 64 KB 80% 100%

This access pattern is designed to be used on hard disk drives to measure their performance when used on file servers. The UDO Desktop drive is by no means a file server hard disk but this access pattern does provide a measure of how the drive performs. We also created a series of access patterns to measure read performance with 512 byte, 16kB and 32kB files.

Finally, we used DVD Decrypter to backup a DVD movie (Gladiator) to the Plasmon Drive.

3. Performance

We'll start by looking at IOMeter's output for the UDO Desktop Drive with the file server access pattern. We allowed the test to run for a period of 5 minutes. We also ran the same test on a Western Digital 80GB EIDE hard disk and a Fujitsu MHV2060AT 60Gb 2.5" drive, and have provided the output from both as a comaprison. While the two hard drives have very little in common with the UDO drive other than providing storage, the comparison does provide a way to judge the UDO Drive's performance and as we will see, there are some surprises.
Operation Plasmon UDO Drive Fujitsu 60 GB mini disk WD800JB 80GB HDD
Read IOps
Write IOps
Read MBps
Write MBps
Transactions per Second 17.19 87.39 155.13
Times are in milliseconds
Avg. Response Time
Avg. Read Response Time
Avg. Write Response Time
Avg. Transaction Time
Max. Response Time
Max. Read Response Time
Max. Write Response Time
Max. Transaction Time
Read Errors
Write Errors
Bytes Read
Bytes Written
Read I/Os
Write I/Os

The Western Digital Hard Disk wins hands down, as we would expect it to. However, the UDO drive does clock in some impressive figures for an optical drive. Its Avg. response times are not that far behind those of either hard disk.

The following table however, should prove more interesting. It shows the UDO Drive's output for 3 separate Iometer configurations, set to 100% reading of 512 byte, 16k byte and 32k byte file sizes. Setting Iometer to 100% reads, more closely simulates the type of work the drive will be expected to carry out. Again, the tests were run for 5 minutes.

Operation 512 bytes 16k bytes 32k bytes
Read IOps 264.10 135.42 67.94
Read MBps 0.13 2.12 2.13
Transactions per Second 264.10 135.42 67.94
Times are in milliseconds
Avg. Read Response Time 3.78 7.38 14.71
Max. Read Response Time 150.48 186.21 116.67
Read Errors 0 0 0
Bytes Read 40,644,096 666,877,952 669,155,328
Read I/Os 79,383 40,703 20,421

It is interesting to see the difference in performance between small files and larger files. At 16k and 32k, the throughput (Read MBps) does not differ by much with 2.12MB/s and 2.13MB/s respectively. For 512 bytes however, it drops to 130kB/s. A similar pattern appears with total amount of bytes read, where for 16k and 32k the figures are fairly close at 636Mb and 638Mb respectively, while for 512 bytes, the corresponding figure is only 39Mb.

The last test we put our UDO drive through was to copy a full DVD movie to the drive. We used DVD Decryptor to copy Gladiator from a Pioneer DVR 108 drive. The process was completed in 1:00:40 with an average read rate of 1,974 KB/s (1.4x) and maximum read rate of 4,167 KB/s (3.0x). As a comparison, the same process but with the copy being written to the Western Digital Hard Disk, had a duration of 00:24:40 with an average read rate of 4,857 KB/s (3.5x) and maximum read rate of 6,949 KB/s (5.0x).

4. Summary

Plasmon has traditionally provided professional archive storage solutions through their G-Series Optical Libraries, supporting both Ultra Density Optical (UDO) and Magneto Optical storage. The UDO Desktop Drive from Plasmon now brings this technology to the PC desktop user. The drive is based on the Blue-laser technology and supports Plasmon's UDO media with capacities of 30GB for both Write Once and Rewritable formats. The Desktop Drive is targeted at small office or departmental applications while there have also been installations of Desktop Drives in combination with library configurations.

We used the drive over a period of 3 months, putting it through its paces and consider it to be a very good solution for small businesses requiring a reliable backup or archiving solution. The drive is not cheap, but according to Plasmon's Archival Storage Total Cost of Ownership Analysis, UDO is one of the most cost effective technologies, especially in terms of maintenance and operation over a long period of time, while also being one of the most reliable.

A very important plus is the fact that as needs dictate, a business can easily upgrade from the Desktop Drive to the G-Series libraries which can accommodate capacities ranging from 720GB up to 19.1TB.

Plasmon also has a number of very interesting case studies available, as well as partner solutions which cover almost any type of archival and backup need.

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