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VTL products in the industry:
Integration: Engine units and storage units are combined, which is applicable to small-capacity devices such as EMC DD160, DD620, IBM TS7610, HP D2D2500, and D2D4100.
Scalable mode: Engine units and storage units are separated. Capacity can be expanded on demand. Most VTL products use this mode.
Gateway-based mode: Engine units can cooperate with third-party disk arrays, which is applicable to switchovers from primary storage to secondary storage. IBM TS7650G and HP VLS12200 are typical examples.
HUAWEI VTL6900-I/IS is an integrated device. The VTL6000-AIO/SOLO/HA/HAS is scalable. The back-end storage of the VTL6900 cannot be replaced. Therefore, the VTL6900 does not use the gateway-based mode.