---
title: DoAsyncSynchronize
framework: BlockStorageDeviceDriverKit
role: symbol
role_heading: Instance Method
platforms: [driverkit 21.0+]
path: blockstoragedevicedriverkit/iouserblockstoragedevice/doasyncsynchronize
---

# DoAsyncSynchronize

Forces the hardware buffer to flush data blocks to the media.

## Declaration

```occ
virtual kern_return_t DoAsyncSynchronize(uint32_t requestID, uint64_t lba, uint64_t numOfBlocks);
```

## Parameters

- `requestID`: An opaque identifier. After the dext completes the request, it calls doc://com.apple.blockstoragedevicedriverkit/documentation/BlockStorageDeviceDriverKit/IOUserBlockStorageDevice/Complete and sends this value as a parameter.
- `lba`: The logical block number of the first block to synchronize.
- `numOfBlocks`: The number of blocks to synchronize.

## Return Value

Return Value A value that indicates the synchronize result. kIOReturnSuccess indicates success. For error definitions, see IOKit Constants.

## Discussion

Discussion When the synchronize operation completes, the dext calls your Complete method with the results of the operation.

## See Also

### Accessing the Device

- [DoAsyncUnmap](blockstoragedevicedriverkit/iouserblockstoragedevice/doasyncunmap.md)
- [BlockRange](blockstoragedevicedriverkit/blockrange.md)
- [DoAsyncEjectMedia](blockstoragedevicedriverkit/iouserblockstoragedevice/doasyncejectmedia.md)
- [Complete](blockstoragedevicedriverkit/iouserblockstoragedevice/complete.md)
- [DoAsyncReadWrite](blockstoragedevicedriverkit/iouserblockstoragedevice/doasyncreadwrite.md)
- [IOUserStorageOptions](blockstoragedevicedriverkit/iouserstorageoptions.md)
- [CompleteIO](blockstoragedevicedriverkit/iouserblockstoragedevice/completeio.md)