<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
FINANCIAL STATEMENTS OF QUANTUM CORPORATION.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C> <C> <C>
<PERIOD-TYPE> 9-MOS 6-MOS 3-MOS
<FISCAL-YEAR-END> MAR-31-1999 MAR-31-1999 MAR-31-1999
<PERIOD-START> APR-01-1998 APR-01-1998 APR-01-1998
<PERIOD-END> DEC-27-1998 SEP-27-1998 JUN-28-1998
<CASH> 683,011 549,446 496,371
<SECURITIES> 24,425 29,240 58,528
<RECEIVABLES> 676,061 673,999 674,825
<ALLOWANCES> 11,823 10,985 11,854
<INVENTORY> 259,042 295,799 317,826
<CURRENT-ASSETS> 1,855,466 1,763,553 1,765,813
<PP&E> 505,707 543,157 524,412
<DEPRECIATION> 278,922 256,909 236,967
<TOTAL-ASSETS> 2,393,568 2,128,804 2,153,016
<CURRENT-LIABILITIES> 663,711 607,578 603,983
<BONDS> 351,725 326,985 327,238
0 0 0
0 0 0
<COMMON> 855,946 802,590 785,827
<OTHER-SE> 448,241 616,189 597,736
<TOTAL-LIABILITY-AND-EQUITY> 2,393,568 2,128,804 2,153,016
<SALES> 3,593,315 2,267,734 1,103,023
<TOTAL-REVENUES> 3,593,315 2,267,734 1,103,023
<CGS> 2,995,964 1,909,473 936,650
<TOTAL-COSTS> 2,995,964 1,909,473 936,650
<OTHER-EXPENSES> 662,088 316,070 155,570
<LOSS-PROVISION> 0 0 0
<INTEREST-EXPENSE> 20,136 13,227 6,502
<INCOME-PRETAX> (84,873) 28,964 4,301
<INCOME-TAX> 1,403 8,689 1,291
<INCOME-CONTINUING> (86,276) 20,275 3,010
<DISCONTINUED> 0 0 0
<EXTRAORDINARY> 0 0 0
<CHANGES> 0 0 0
<NET-INCOME> (86,276) 20,275 3,010
<EPS-BASIC> (0.54) 0.13 0.02
<EPS-DILUTED> (0.54) 0.13 0.02
</TABLE>