# kIOPropertyLogicalBlockSizeKey ``` #define kIOPropertyLogicalBlockSizeKey ``` ## 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: ```objc Device Characteristics Vendor Name Apple Product Name iPod Product Revision Level 1.0 Physical Block Size 4096 Logical Block Size 512 ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)