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# DeviceParams

A structure that represents hardware-specific properties of the block storage device.

```
struct DeviceParams;
```

## Discussion

Implement the [`GetDeviceParams`](/documentation/BlockStorageDeviceDriverKit/IOUserBlockStorageDevice/GetDeviceParams) method to provide the framework with the device-specific properties indicated by this structure.

## Topics

### Accessing Device Parameters

[`uint64_t numOfBlocks;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/numOfBlocks)

The number of blocks on the device.

[`uint32_t blockSize;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/blockSize)

The size of a block on the device.

[`uint32_t maxIOSize;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/maxIOSize)

The maximum amount of data per I/O call.

[`uint32_t numOfOutstandingIOs;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/numOfOutstandingIOs)

The upper limit to the number of requests sent to the device.

[`uint32_t maxNumOfUnmapRegions;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/maxNumOfUnmapRegions)

The maximum number of regions supported by an unmap call.

[`uint32_t minSegmentAlignment;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/minSegmentAlignment)

The minimum alignment of the data buffer sent to read-write calls.

[`uint8_t numOfAddressBits;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/numOfAddressBits)

The number of bits used to address blocks on the device.

[`bool isUnmapSupported;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/isUnmapSupported)

A Boolean value that indicates whether the device supports unmapping to reclaim storage.

[`bool isFUASupported;`](/documentation/BlockStorageDeviceDriverKit/DeviceParams/isFUASupported)

A Boolean value that indicates whether the device supports forced unit access (FUA).


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