Magnetic tape cartridge and magnetic recording and reproducing device

A magnetic tape cartridge comprising:

• a medium, which is a magnetic tape,
• wherein the magnetic tape is wound around a cartridge reel and accommodated in the magnetic tape cartridge,
• the magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder,
• the magnetic layer includes a plurality of servo bands,
• in a case where a maximum value of an absolute value of a difference between a servo band spacing obtained before storage in an environment of a temperature of 32° C. and relative humidity of 55% and a servo band spacing obtained after storage in the environment for a storage time T is set to A, a unit of A is μm, and T is defined as 24 hours, 48 hours, 72 hours, 96 hours, or 120 hours, a medium life calculated by a linear function of A and a logarithm logeT of T, that are derived from a value of A and a value of the logarithm logeT of T obtained for each T is 3 years or longer,
• the medium life is the storage time T when A satisfies Equation 1:
• A=1.5−B, and (Equation 1)
• the B is a value calculated by multiplying a difference between a maximum value and a minimum value of the servo band spacings obtained
• in each of the following five environments of
• a temperature of 16° C. and relative humidity of 20%,
• a temperature of 16° C. and relative humidity of 80%,
• a temperature of 26° C. and relative humidity of 80%,
• a temperature of 32° C. and relative humidity of 20%, and
• a temperature 32° C. and relative humidity of 55%,
• by ½, and the unit is μm.