<PAGE>


                                  EXHIBIT 10.5

                               RETENTION AGREEMENT



                  THIS RETENTION AGREEMENT (the "AGREEMENT"), dated March 12,
2001, is made by and between Overland Data Inc., a California corporation having
its principal offices at 8975 Balboa Avenue, San Diego, California 92123-1599
(the "COMPANY") and Christopher Calisi ("EMPLOYEE").

                                    AGREEMENT

         WHEREAS, Employee is a key employee of the Company;

         WHEREAS, the Company considers that providing Employee with certain
employment termination benefits will operate as an incentive for Employee to
remain employed by the Company in the event of a Change of Control.

         NOW THEREFORE, to induce Employee to remain employed by the Company,
and for other good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, the Company and Employee agree as follows:

1.       DEFINITIONS.

         1.1      "BASE SALARY" shall mean the Employee's gross annual salary at
the time of a Change of Control or the Termination Date, whichever is higher.

         1.2      "CHANGE OF CONTROL" is defined to have occurred if, and only
if, during Employee's employment:

                  (a)      any individual, partnership, firm, corporation,
association, trust, unincorporated organization or other entity or person, or
any syndicate or group deemed to be a person under Section 14(d)(2) of the
Exchange Act is or becomes the "Beneficial Owner" (as defined in Rule 13d-3 of
the General Rules and Regulations under the Exchange Act), directly or
indirectly, of securities of the Company representing 50% or more of the
combined voting power of the Company's then outstanding securities entitled to
vote in the election of directors of the Company;

                  (b)      there occurs a reorganization, merger, consolidation
or other corporate transaction involving the Company ("TRANSACTION"), in each
case, with respect to which the stockholders of the Company immediately prior to
such Transaction do not, immediately after the Transaction, own more than fifty
(50) percent of the combined voting power of the Company or other corporation
resulting from such Transaction; or

                  (c)      all or substantially all of the assets of the Company
are sold, liquidated or distributed.


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         1.3      "CAUSE" shall mean:

                  (a)      Employee's gross neglect of his duties to the
Company, where Employee has been given a reasonable opportunity to cure his
gross neglect (which reasonable opportunity must be granted during the
thirty-day period preceding termination);

                  (b)      any violation by Employee of Employee's obligations
under this Agreement or any employment agreement which Employee may have with
the Company;

                  (c)      Employee taking any role in any buy-out of the
Company without the approval of the Company's majority shareholder; or

                  (d)      Employee's commission of any act of fraud, theft or
embezzlement against the Company.

         1.4      "COMPENSATION" shall mean Base Salary plus Target Bonus.

         1.5      "RESIGNATION FOR GOOD REASON" shall mean the voluntary
resignation by Employee of his employment with the Company within two years
following a Change of Control and within three (3) months of the following Good
Reasons:

                  (a)      any reduction in Employee's Base Salary or Target
Bonus; or

                  (b)      any reduction in Employee's title; or

                  (c)      any significant reduction in Employee's
responsibilities and authority;

                  (d)      any failure by the Company to pay Employee's Base
Salary; or

                  (e)      a relocation by the Company of Employee's place of
Employment outside a fifty (50) mile radius of Employee's current place of
employment.

                  An event described in Section 1.5(a) through (e) will not
constitute Good Reason unless Employee provides written notice to the Company of
his intention to resign for Good Reason and unless the Company does not cure the
Good Reason within ten (10) days of the Company's receipt of the written notice.

         1.6      "SEVERANCE PERIOD" shall begin on the Termination Date and
extend for twelve months following the Termination Date.

         1.7      "TARGET BONUS" shall mean the variable annual compensation
represented by the percentage of Base Salary Employee is eligible to receive,
prior to a Change of Control, in the event targeted goals are achieved for the
year.

         1.8      "TERMINATION DATE" shall mean the date of termination of
Employee's employment relationship with the Company.

         1.9      "TERMINATION PAYMENTS" shall mean any payment or distribution
of Compensation or benefits made pursuant to SECTION 4.1 (a)-(c) of this
Agreement.


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2.       TITLE AND DUTIES. Employee will hold the position of President and
Chief Executive Officer. His primary duties will include such duties as are
assigned or delegated to Employee by the Company's Board of Directors. Employee
will: (i) devote his entire business time, attention, skill, and energy
exclusively to the business of the Company; (ii) use his best efforts to promote
the success of the Company's business; and (iii) cooperate fully with the Board
of Directors of the Company in the advancement of the best interests of the
Company.

3.       AT-WILL EMPLOYMENT. Employee reaffirms that Employee's employment
relationship with the Company is at-will, terminable at any time and for any
reason by either the Company or Employee. While certain paragraphs of this
Agreement describe events that could occur at a particular time in the future,
nothing in this Agreement may be construed as a guarantee of employment of any
length.

4.       TERMINATION PAYMENTS.

         4.1      If, within two (2) years immediately following a Change of
Control, Employee's employment terminates as the result of (i) termination by
the Company of Employee's employment for a reason other than Cause; or (ii)
Employee's Resignation for Good Reason

                  (a)      Employee will receive a pro-rata share of Base Salary
and accrued but unused vacation through the Termination Date, less applicable
state and federal taxes or other payroll deduction;

                  (b)      Employee is eligible for Severance under this
Agreement in a lump-sum amount equal to Base Salary plus Target Bonus,
multiplied by 2.5, less applicable state and federal taxes or other payroll
deduction;

                  (c)      If Employee elects to continue insurance coverage as
afforded to Employee according to the Consolidated Omnibus Budget Reconciliation
Act of 1985 ("COBRA"), Company will reimburse Employee the amount of the
premiums incurred by Employee during the Severance Period. Nothing in this
Agreement will extend Employee's COBRA period beyond the period allowed under
COBRA, nor is Company assuming any responsibility which Employee has for
formally electing to continue coverage;

         4.2      The payments set forth in SECTIONS 4.1(b) AND (c) above are in
exchange for, and contingent upon Employee's execution of a release of all
claims as of the Termination Date, in substantially the form attached to this
Agreement as Exhibit 1.

         4.3      If Employee's employment terminates for any reason after the
two year period immediately following a Change of Control or terminates during
that two year period for any reason other than (i) termination by the Company of
Employee's employment for a reason other than Cause; or (ii) Employee's
Resignation for Good Reason, the Company will pay Employee a pro-rata share of
Base Salary and accrued but unused vacation through the Termination Date.

         4.4      If Employee resigns his employment for Good Reasons described
in Section 1.5 (b) or (c) above, payment of the above Termination Payments is
contingent upon Employee's willingness, at the Company's request, to continuing
performing his duties on behalf of the Company in good faith for up to ninety
(90) days following the occurrence of the events


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<PAGE>


described in these Sections 1.5 (b) and (c). Employee will continue to receive
his regular Base Salary paid according to the Company's regular payroll
practices during the up-to ninety (90) day period and will receive the
Termination Payment upon completion of that period.

5.       RETIREMENT AND PROFIT-SHARING PLANS. Notwithstanding anything in this
Agreement to the contrary, Employee's rights in any retirement, pension or
profit-sharing plans offered by the Company shall be governed by the rules of
such plans as well as by applicable law; provided, however, that on the
Termination Date, Employee shall become fully vested in all pension and 401(k)
account balances.

6.       TAX CONSEQUENCES. The Company makes no representations regarding the
tax consequence of any provision of this Agreement. Employee is advised to
consult with his own tax advisor with respect to the tax treatment of any
payment contained in this Agreement.

7.       TAX ADJUSTMENT. Notwithstanding the foregoing or any other provision of
this Agreement to the contrary, if tax counsel selected by the Company and
acceptable to Employee determines that any portion of any payment under this
Agreement would constitute an "excess parachute payment" within the meaning of
Section 280G of the Internal Revenue Code of 1986, as amended (the "Code"), the
payments to be made to Employee under this Agreement shall be reduced (but not
below zero) such that the value of the aggregate payments that Employee is
entitled to receive under this Agreement and any other agreement or plan or
program of the Company shall be one dollar ($1) less than the maximum amount of
payments which Employee may receive without becoming subject to the tax imposed
by Section 4999 of the Code.

8.       DISPUTE RESOLUTION PROCEDURES. Any dispute or claim arising out of this
agreement shall be subject to final and binding arbitration. The arbitration
will be conducted by one arbitrator who is a member of the American Arbitration
Association ("AAA") or of the Judicial Arbitration and Mediation Services
("JAMS"). The arbitration shall be held in San Diego, California. The arbitrator
shall have all authority to determine the arbitrability of any claim and enter a
final and binding judgment at the conclusion of any proceedings in respect of
the arbitration. Any final judgment only may be appealed on the grounds of
improper bias or improper conduct of the arbitrator. The parties will be
entitled to conduct discovery (i.e., investigation of facts through depositions
and other means) which shall be governed by the California Code of Civil
Procedure (the "CCP") section 1283.05. The arbitrator shall have all power and
authority to enter orders relating to such discovery as are allowed under the
CCP. The arbitrator will apply California substantive law in all respects. The
party prevailing in the resolution of any such claim will be entitled, in
addition to such other relief as may be granted, to an award of all reasonable
attorneys fees and costs incurred in pursuit of the claim, without regard to any
statute, schedule, or rule of court purported to restrict such award.

9.       GENERAL PROVISIONS.

         9.1      GOVERNING LAW. This Agreement will be governed by and
construed in accordance with the laws of California.

         9.2      ASSIGNMENT. Employee may not assign, pledge or encumber his
interest in this Agreement or any part thereof.


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<PAGE>


         9.3      NO WAIVER OF BREACH. The failure to enforce any provision of
this Agreement will not be construed as a waiver of any such provision, nor
prevent a party from enforcing the provision or any other provision of this
Agreement. The rights granted the parties are cumulative, and the election of
one will not constitute a waiver of such party's right to assert all other legal
and equitable remedies available under the circumstances.

         9.4      SEVERABILITY. The provisions of this Agreement are severable,
and if any provision will be held to be invalid or otherwise unenforceable, in
whole or in part, the remainder of the provisions, or enforceable parts of this
Agreement, will not be affected.

         9.5      ENTIRE AGREEMENT. This Agreement constitutes the entire
agreement of the parties with respect to the subject matter of this Agreement,
and supersedes all prior and contemporaneous negotiations, agreements and
understandings between the parties, oral or written.

         9.6      MODIFICATION; WAIVERS. No modification, termination or
attempted waiver of this Agreement will be valid unless in writing, signed by
the party against whom such modification, termination or waiver is sought to be
enforced.

         9.7      FEES AND EXPENSES. If any proceeding is brought for the
enforcement or interpretation of this Agreement, or because of any alleged
dispute, breach, default or misrepresentation in connection with any provisions
of this Agreement, the successful or prevailing party will be entitled to
recover from the other party reasonable attorneys' fees and other costs incurred
in that proceeding (including, in the case of an arbitration, arbitration fees
and expenses), in addition to any other relief to which such party may be
entitled.

         9.8      AMENDMENT. This Agreement may be amended or supplemented only
by a writing signed by both of the parties hereto.

         9.9      DUPLICATE COUNTERPARTS. This Agreement may be executed in
duplicate counterparts; each of which shall be deemed an original; provided,
however, such counterparts shall together constitute only one instrument.

         9.10     INTERPRETATION. The headings contained in this Agreement are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.


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<PAGE>


         9.11     DRAFTING AMBIGUITIES. Each party to this Agreement and its
counsel have reviewed and revised this Agreement. The rule of construction that
any ambiguities are to be resolved against the drafting party shall not be
employed in the interpretation of this Agreement or any of the amendments to
this Agreement.



                                   OVERLAND DATA, INC.



Dated:  2-21-01                    By:  /s/ Vernon A. LoForti
                                      ------------------------------------------
                                      Vernon A. LoForti,
                                      Vice President and Chief Financial Officer




Dated:  2-21-01                         /s/ Christopher Calisi
                                      ------------------------------------------
                                      Christopher Calisi


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<PAGE>


                                    EXHIBIT 1

                                 GENERAL RELEASE

This GENERAL RELEASE ("RELEASE") is entered into effective as of ______________,
____, (the "EFFECTIVE DATE") by and between Overland Data, Inc., a California
corporation, having its principal offices at 8975 Balboa Avenue, San Diego,
California 92123-1599 ("COMPANY") and Christopher Calisi, an individual residing
at ________________________________ ("EMPLOYEE") with reference to the following
facts:

                                    RECITALS

         A.       The parties entered into a Retention Agreement ("the
Agreement") dated March 12, 2001, by which the parties agreed that upon the
occurrence of certain conditions, Employee would become eligible for Termination
Payments as defined in the Agreement in exchange for Employee's release of the
Company from all claims which Employee may have against the Company as of the
Termination Date.

         B.       The parties desire to dispose of, fully and completely, all
claims, which Employee may have against the Company in, the manner set forth in
this Release.

                                    AGREEMENT

         1.       RELEASE. Employee, for himself and his heirs, successors and
assigns, each fully releases, and discharges Company, its officers, directors,
employees, shareholders, attorneys, accountants, other professionals, insurers
and agents of the other (collectively "Agents"), and all entities related to
each party, including, but not limited to, heirs, executors, administrators,
personal representatives, assigns, parent, subsidiary and sister corporations,
affiliates, partners and co-venturers (collectively "Related Entities"), from
all rights, claims, demands, actions, causes of action, liabilities and
obligations of every kind, nature and description whatsoever, Employee now has,
owns or holds or has at anytime had, owned or held or may have against the
Company, Agents or Related Entities from any source whatsoever, whether or not
arising from or related to the facts recited in this Release. Employee
specifically releases and waives any and all claims arising under any express or
implied contract, rule, regulation or ordinance, including, without limitation,
Title VII of the Civil Rights Act of 1964, the Civil Rights Act of 1991, the
Americans with Disabilities Act, the California Fair Employment and Housing Act,
and the Age Discrimination in Employment Act, as amended ("ADEA").

         2.       SECTION 1542 WAIVER. This Release is intended as a full and
complete release and discharge of any and all claims that Employee may have
against the Company, Agents or Related Entities. In making this release,
Employee intends to release the Company, Agents and Related Entities from
liability of any nature whatsoever for any claim of damages or injury or for
equitable or declaratory relief of any kind, whether the claim, or any facts on
which such claim might be based, is known or unknown to him. Employee expressly
waives all rights under ss.1542 of the California Civil Code, which Employee
understands provides as follows:


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<PAGE>


                      A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE
                      CREDITOR DOES NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT
                      THE TIME OF EXECUTING THE RELEASE, WHICH IF KNOWN BY HIM
                      MUST HAVE MATERIALLY AFFECTED HIS SETTLEMENT WITH THE
                      DEBTOR.

Employee acknowledges that he may discover facts different from or in addition
to those that he now believes to be true with respect to this Release. Employee
agrees that this Release shall remain effective notwithstanding the discovery of
any different or additional facts.

         3.       WAIVER OF CERTAIN CLAIMS. Employee acknowledges that he has
been advised in writing of his right to consult with an attorney prior to
executing the waivers set out in this Release, and that he has been given a
21-day period in which to consider entering into the release of ADEA claims, if
any. In addition, Employee acknowledges that he has been informed that he may
revoke a signed waiver of the ADEA claims for up to seven (7) days after
executing this Release.

         4.       NO UNDUE INFLUENCE. This Release is executed voluntarily and
without any duress or undue influence. Employee acknowledges he has read this
Release and executed it with his full and free consent. No provision of this
Release shall be construed against any party by virtue of the fact that such
party or its counsel drafted such provision or the entirety of this Release.

         5.       GOVERNING LAW. This Release is made and entered into in the
State of California and accordingly the rights and obligations of the parties
hereunder shall in all respects be construed, interpreted, enforced and governed
in accordance with the laws of the State of California as applied to contracts
entered into by and between residents of California to be wholly performed
within California.

         6.       SEVERABILITY. If any provision of this Release is held to be
invalid, void or unenforceable, the balance of the provisions of this Release
shall, nevertheless, remain in full force and effect and shall in no way be
affected, impaired or invalidated.

         7.       COUNTERPARTS. This Release may be executed simultaneously in
one or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument. This Release may be
executed by facsimile, with originals to follow by overnight courier.

         8.       DISPUTE RESOLUTION PROCEDURES. Any dispute or claim arising
out of this Release shall be subject to final and binding arbitration. The
arbitration will be conducted by one arbitrator who is a member of the American
Arbitration Association (AAA) or of the Judicial Arbitration and Mediation
Services (JAMS) and will be governed by the Model Employment Arbitration rules
of AAA. The arbitration shall be held in San Diego, California. The arbitrator
shall have all authority to determine the arbitrability of any claim and enter a
final and binding judgment at the conclusion of any proceedings in respect of
the arbitration. Any final judgment only may be appealed on the grounds of
improper bias or improper conduct of the arbitrator. Notwithstanding any rule of
AAA to the contrary, the parties will be entitled to conduct


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<PAGE>


discovery (i.e. investigation of facts through depositions and other means)
which shall be governed by California Code of Civil Procedure Section 1283.05
(the "CCP"). The arbitrator shall have all power and authority to enter orders
relating to such discovery as are allowed under the CCP. The arbitrator will
apply California substantive law in all respects. The party prevailing in the
resolution of any such claim will be entitled, in addition to such other relief
as may be granted, to an award of all actual attorneys fees and costs incurred
in pursuit of the claim, without regard to any statute, schedule, or rule of
court purported to restrict such award.

         9.       ENTIRE AGREEMENT. This Agreement constitutes the entire
agreement of the parties with respect to the subject matter of this Agreement,
and supersedes all prior and contemporaneous negotiations, agreements and
understandings between the parties, oral or written.

         10.      MODIFICATION; WAIVERS. No modification, termination or
attempted waiver of this Agreement will be valid unless in writing, signed by
the party against whom such modification, termination or waiver is sought to be
enforced.

         11.      AMENDMENT. This Agreement may be amended or supplemented only
by a writing signed by Employee and the Company.



Dated:
      ------------------------------------  ------------------------------------
                                            Christopher Calisi


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