---
title: kIOPropertyLogicalBlockSizeKey
framework: driverkit
role: symbol
role_heading: Macro
path: driverkit/kiopropertylogicalblocksizekey
---

# kIOPropertyLogicalBlockSizeKey

## Declaration

```occ
#define kIOPropertyLogicalBlockSizeKey
```

## Discussion

Discussion This key is used to define the logical block size of a hard disk drive. Requirement: Mandatory for hard disk drives with logical block size other than 512 bytes or that does not match its physical block size. Example:     <dict>    <key>Device Characteristics</key>    <dict>    	<key>Vendor Name</key>    	<string>Apple</string>    	<key>Product Name</key>    	<string>iPod</string>    	<key>Product Revision Level</key>    	<string>1.0</string>    	<key>Physical Block Size</key>    	<integer>4096</integer>    	<key>Logical Block Size</key>    	<integer>512</integer>    </dict> </dict>

## See Also

### Macros

- [ALWAYS](driverkit/always.md)
- [APPLE_KEXT_OVERRIDE](driverkit/apple_kext_override.md)
- [DEFN](driverkit/defn.md)
- [DRIVERKIT_CONSUMED](driverkit/driverkit_consumed.md)
- [DRIVERKIT_CONSUMES_THIS](driverkit/driverkit_consumes_this.md)
- [DRIVERKIT_FRAMEWORK_INCLUDE](driverkit/driverkit_framework_include.md)
- [DRIVERKIT_IOLIB_H](driverkit/driverkit_iolib_h.md)
- [DRIVERKIT_OSCOLLECTIONS_H](driverkit/driverkit_oscollections_h.md)
- [DRIVERKIT_RETURNS_NOT_RETAINED](driverkit/driverkit_returns_not_retained.md)
- [DRIVERKIT_RETURNS_RETAINED](driverkit/driverkit_returns_retained.md)
- [DRIVERKIT_RETURNS_RETAINED_ON_NONZERO](driverkit/driverkit_returns_retained_on_nonzero.md)
- [DRIVERKIT_RETURNS_RETAINED_ON_ZERO](driverkit/driverkit_returns_retained_on_zero.md)
- [ERR_SUCCESS](driverkit/err_success.md)
- [EXTENDS](driverkit/extends.md)
- [HIDDEN](driverkit/hidden.md)