Filed by Quantum Corporation Pursuant to Rule 425
Under the Securities Act of 1933
And Deemed Filed Pursuant to Rule 14a-12
Under the Securities Exchange Act of 1934
Subject Company: Advanced Digital Information Corporation
Commission File No.: 0-21103

Quantum and ADIC: A Great Combination
May 2, 2006

What We are Announcing Today
The two leading, independent backup, recovery and archive providers… are joining together to give customers…
the most comprehensive and integrated range of solutions for securely storing, managing, protecting and recovering their data in open systems IT environments
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

The Opportunity
Unprecedented Opportunity for a Storage Industry Innovator to Deliver Integrated Backup, Recovery and Archive Solutions
Data growth rates show no signs of slowing Storage remains a top IT decision-maker priority Regulatory compliance issues increase storage complexity, risk and cost Existing storage architectures no longer meeting requirements Users seeking trusted suppliers that can deliver best-of-breed solutions Constrained IT budgets dictate strong focus on total cost of ownership
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

$20 Billion Growth Market
Target Market Represents Growth Opportunity that is 2x the Rate of Storage Industry Overall
Total Storage Market End-user Revenue $ Billions
Total | | Storage Market 2006 CAGR% |
Network | | Infrastructure $3.2 17.5% |
Management | | Software $8.9 11.6% |
Tape | | Devices / Systems $7.9 5.1% |
Host-Attached | | Disk $7.3 -5.5% |
“Recovery” Storage Market End-user Revenue $ Billions
Recovery | | Storage Market 2006 CAGR% |
Recovery | | Services $0.08 14.9% |
Recovery | | Net. Infra. $1.3 23.8% |
Recovery | | Mgmt. Software $5.3 12.0% |
Tape | | Devices / Systems $7.9 5.1% |
Recovery | | Disk Systems $4.9 15.7% |
CAGR% for 2003-2008
Source: IDC
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Strategic Rationale
Unequalled portfolio of innovative backup, recovery and archive solutions Outstanding customer access & go-to-market infrastructure High relevance to target customers, channel partners and OEMs Best-in-class global service delivery Broad scale across systems, software, devices, and media portfolio Increased financial strength expands investment opportunities in high growth areas Deep base of R&D expertise facilitates greater innovation
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Delivering Greater Value to Customers and Partners
Coming together to become the largest independent provider of backup, recovery and archive solutions
Address customers evolving data protection, retention and recovery needs
Most comprehensive and integrated range of solutions
Unparalleled portfolio of systems, software, devices, media and service capabilities
Benefits of scale and integration, and a single source of intelligent and innovative products and services
Deliver unsurpassed value to customers and partners
Financially positioned to invest in new solutions to address emerging storage challenges
Much stronger go-to-market infrastructure
Larger and better leveraged sales and service capabilities
Enhanced support for channel partners, OEMs and end-users
Broader base of R&D expertise provides opportunities for greater innovation
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Broad Coverage of User Needs
Plug & play Price & value Simplicity Reliability
Phone & web support Warranty
Volume channel System & regional OEMs
Low-cost manufacturing
Point solutions Flexibility Reliability TCO
On-site & technical support Warranty
Diverse channel System & regional OEMs
Low-cost / flexible manufacturing
Total solutions Performance RAS
Interoperability ROI
Global on-site & technical support
Enterprise sales channel
Configure-to-order manufacturing
Workgroup Midrange Enterprise
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Broad Coverage of User Needs
Workgroup Midrange Enterprise
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Extensible Solutions Platform
Our Vision: Comprehensive and integrated solutions for securely storing, managing, protecting and recovering data in open systems IT environments
Core Backup & Recovery
Remote Site Disaster Recovery
Workflow & Archiving
Tiered Data Center Storage
Data Mgmt.
Storage Security
Scalar 10k
DX-Series
DPM5500
Scalar i500
SuperLoader 3
PX720
Pathlight VX
Scalar i2000
PX500 Series
FastStor iSurety
Global Services
Guardian
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Award-Winning Global Services
Over 700 Service Team Members (+ Partners)
Over 400 Strategic Stocking Locations
90 Countries Covered
Leadership in Enabling Technology
(iSurety, Guardian)
>50 Product Lines Supported >18k Contracts
Eight Technical Assistance Centers
2005, 2006 NorthFace Award
Customer Sat. Excellence
2005 Positive Rating
Support / Acct. Management
2006 SSPA STAR Award
Best Practices in Support
2004, 2005, 2006 SCP Certified
Support Effectiveness
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Value Across the Channel
Globally deployed solution & technical sales teams delivering users and partners unequalled industry expertise Loyal enterprise VARs focused on delivering comprehensive data storage, management, protection and recovery solutions Highly effective high-volume channel delivering workgroup solutions through distribution Recognized for best-in-class channel engagement, support and programs
CRN Channel Chiefs
VAR Business 5 Star Partner Program Winner
VARBusiness Top 100 Channel Executives
CRN Channel Champions Finalist
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Trusted by Global IT Leaders
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Transaction Summary
Definitive agreement signed May 2
ADIC to be acquired for $12.25 per share (approximately $770M total)
Cash transaction
Shareholders may opt to receive Quantum stock
Approximately $45 million in annual cost synergies
Up to 15 cents accretive on cash EPS basis in first year full year after closing
Transaction subject to regulatory and ADIC shareholder approval
Deal expected to close in 3-4 months
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

The Combined Company
Over $1.2B in revenues Over 3000 employees Significant global presence
Substantial customer access capabilities:
3x the sales force and 2x the service sales force Broad base of OEM relationships Over 250 enterprise VARs Over 5,000 VARs actively selling product each quarter Over 200,000 automation systems installed in the last four years Almost 20,000 systems covered by service uplift contracts
Deep R&D expertise across the core business and emerging segments
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Industry Analyst Reaction
“This is a brilliant strategic move by Quantum and great news for customers. The combined company will have an enormous set of offerings, the scale, footprint and financial foundation to really have an impact in the data protection market. This acquisition propels Quantum into a clear top three position among the largest data protection suppliers, and makes them big enough to control their own fate. I love this deal.”
— Steve Duplessie
Founder and Senior Analyst Enterprise Strategy Group
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Succeeding Together
Significant market opportunity Compelling strategic rationale Outstanding global team Customer-centric culture Complementary assets and capabilities Extensive, synergistic solutions portfolio Financial strength
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Additional Information and Where to Find It
Quantum plans to file with the SEC a Registration Statement on Form S 4 in connection with the transaction, and ADIC plans to file with the SEC and mail to its stockholders a Proxy Statement/Prospectus in connection with the transaction. The Registration Statement and the Proxy Statement/Prospectus will contain important information about Quantum, ADIC, the transaction and related matters. Investors and stockholders are urged to read the Registration Statement and the Proxy Statement/Prospectus carefully when they are available. Investors and stockholders will be able to obtain free copies of the Registration Statement and the Proxy Statement/Prospectus and other documents filed with the SEC by Quantum and ADIC through the web site maintained by the SEC at www.sec.gov. In addition, investors and stockholders will be able to obtain free copies of the Registration Statement and the Proxy Statement/Prospectus from Quantum by contacting Investor Relations at (408) 944-4450 or IR@quantum.com, or from ADIC by contacting Stacie Timmermans at (425) 881-8004 or stacie.timmermans@adic.com.
Quantum and its directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of ADIC in connection with the transaction described herein. Information regarding the special interests of these directors and executive officers in the transaction described herein will be included in the Proxy Statement/Prospectus described above.
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.

Forward-Looking Statements
This presentation contains forward-looking statements within the meaning of the federal securities laws including, without limitation, statements regarding the following: the merger transaction and the benefits and synergies of the merger; expectation that target market represents growth opportunity compared to growth of storage industry; expected benefits of increased financial strength; and the revenues, partners, markets, customers, products and technologies of the combined company. These forward-looking statements are subject to risks and uncertainties as well as assumptions that could cause the actual results of Quantum to differ materially from those expressed or implied by such forward-looking statements.
Such risks and uncertainties include, among others, the following: the approval of the transaction by the stockholders of ADIC; the satisfaction of closing conditions to the transaction, including the receipt of regulatory approvals; the successful and timely integration of ADIC operations, technologies and employees with those of Quantum; the ability to realize the anticipated benefits or synergies of the transaction in a timely manner or at all; fluctuations in the demand for the products of the combined company; possible development or marketing delays relating to product offerings of the combined company; the introduction of new products or technologies by competitors; and the ability of the combined company to achieve expected operating and financial results. A detailed discussion of other risks and uncertainties that could cause actual results or events to differ materially from such forward-looking statements is included in Quantum’s and ADIC’s most recent filings with the Securities and Exchange Commission. Quantum and ADIC undertake no obligation and do not intend to update these forward-looking statements to reflect events or circumstances occurring after this presentation.
©2006 Quantum Corporation. Forward-looking information is based upon multiple assumptions and uncertainties, does not necessarily represent the company’s outlook and is for planning purposes only.