---
title: maxIOSize
framework: BlockStorageDeviceDriverKit
role: symbol
role_heading: Instance Property
platforms: [driverkit 21.0+]
path: blockstoragedevicedriverkit/deviceparams/maxiosize
---

# maxIOSize

The maximum amount of data per I/O call.

## Declaration

```occ
uint32_t maxIOSize;
```

## See Also

### Accessing Device Parameters

- [numOfBlocks](blockstoragedevicedriverkit/deviceparams/numofblocks.md)
- [blockSize](blockstoragedevicedriverkit/deviceparams/blocksize.md)
- [numOfOutstandingIOs](blockstoragedevicedriverkit/deviceparams/numofoutstandingios.md)
- [maxNumOfUnmapRegions](blockstoragedevicedriverkit/deviceparams/maxnumofunmapregions.md)
- [minSegmentAlignment](blockstoragedevicedriverkit/deviceparams/minsegmentalignment.md)
- [numOfAddressBits](blockstoragedevicedriverkit/deviceparams/numofaddressbits.md)
- [isUnmapSupported](blockstoragedevicedriverkit/deviceparams/isunmapsupported.md)
- [isFUASupported](blockstoragedevicedriverkit/deviceparams/isfuasupported.md)