A system startup method performed by a system startup apparatus, the method comprising the steps of: • establishing (step 11) a mapping relationship between an address space of a first storage device and an address space of a second storage device if it is detected that data is incapable of being normally written to the first storage device or a preset instruction of a user is received, wherein the establishing the mapping relationship between the address space of the first storage device and the address space of the second storage device if it is detected that the data is incapable of being normally written to the first storage device or the preset instruction of the user is received comprises: o after a system is powered on, when a boot loader program or a kernel program or an initializer program runs, detecting whether the data is normally written to the first storage device or the preset instruction of the user is received; and o establishing the mapping relationship between the address space of the first storage device and the address space of the second storage device if it is detected that the data is incapable of being normally written to the first storage device or the preset instruction of the user is received; • receiving (step 12) a read/write request sent to the first storage device, wherein the read/write request is used to obtain or store data required during system startup; • if (step 13) the read/write request is a write request for the first storage device, writing data to a second address in the second storage device based on a first address in the first storage device in the write request and the mapping relationship; or if (step 14) the read/write request is a read request for the first storage device, determining whether data has been written, in this startup process, to a fourth address corresponding to a third address in the read request; and reading (step 15) data from the fourth address if determining that the data has been written to the fourth address in this startup process; or, reading data from the third address if determining that no data has been written to the fourth address in this startup process. • establishing (step 11) a mapping relationship between an address space of a first storage device and an address space of a second storage device if it is detected that data is incapable of being normally written to the first storage device or a preset instruction of a user is received, wherein the establishing the mapping relationship between the address space of the first storage device and the address space of the second storage device if it is detected that the data is incapable of being normally written to the first storage device or the preset instruction of the user is received comprises: o after a system is powered on, when a boot loader program or a kernel program or an initializer program runs, detecting whether the data is normally written to the first storage device or the preset instruction of the user is received; and o establishing the mapping relationship between the address space of the first storage device and the address space of the second storage device if it is detected that the data is incapable of being normally written to the first storage device or the preset instruction of the user is received; o after a system is powered on, when a boot loader program or a kernel program or an initializer program runs, detecting whether the data is normally written to the first storage device or the preset instruction of the user is received; and o establishing the mapping relationship between the address space of the first storage device and the address space of the second storage device if it is detected that the data is incapable of being normally written to the first storage device or the preset instruction of the user is received; • receiving (step 12) a read/write request sent to the first storage device, wherein the read/write request is used to obtain or store data required during system startup; • if (step 13) the read/write request is a write request for the first storage device, writing data to a second address in the second storage device based on a first address in the first storage device in the write request and the mapping relationship; or if (step 14) the read/write request is a read request for the first storage device, determining whether data has been written, in this startup process, to a fourth address corresponding to a third address in the read request; and reading (step 15) data from the fourth address if determining that the data has been written to the fourth address in this startup process; or, reading data from the third address if determining that no data has been written to the fourth address in this startup process. if (step 14) the read/write request is a read request for the first storage device, determining whether data has been written, in this startup process, to a fourth address corresponding to a third address in the read request; and reading (step 15) data from the fourth address if determining that the data has been written to the fourth address in this startup process; or, reading data from the third address if determining that no data has been written to the fourth address in this startup process.