RAID....
No, not the famous bug spray, not elite British commandos, not LA S.W.A.T. teams, nor even hunger-crazed teens descending on your fridge...
(R)edundant (A)rray of (I)nexpensive (D)isks... depending on the balance of reading, writing, volatility, etc... you may want to look into RAID 1 (Mirrored array) or RAID 5 (Striped array with parity)...
Of course it may be expensive; but if anyone asks about the cost, compare mantime to restore versus onetime cost of new hardware/implementation (yes I know it's more than that; but this forum doesn't need the whole thing)
Of course, there are many other components that might fail and I'd advise looking into building a full contingency plan for component failure of all types... CPU, Memory, Disk, Network, Tape, etc... and possibly even site failure (fear, flood, fire, foe, etc.)...
Good Luck!!

JTB
Solutions Architect
MCSE-NT4, MCP+I, MCP-W2K, CCNA, CCDA,
CTE, MCIWD, i-Net+, Network+
(MCSA, MCSE-W2K, MCIWA, SCSA, SCNA in progress)