Partition mapping, track layout & NVMe storage geometry

Storage device geometry and addressing mechanisms determine how partitions should be aligned for optimal I/O throughput and SSD longevity. This page covers Logical Block Addressing (LBA), 4Kn Advanced Format with 4096-byte native sectors, and Flash Translation Layers in solid-state drives.

1. Logical Block Addressing (LBA)

Storage devices present their media to the operating system as a linear sequence of indexed blocks using Logical Block Addressing (LBA):

• LBA 0 represents the first addressable block on the disk (containing the primary partition table header).
• LBA $N-1$ represents the final addressable block (housing the GPT backup header on GPT disks).
• The storage controller internally handles the translation between logical LBA numbers and physical media structures.

2. 4Kn Advanced Format (4096-byte Native Sectors)

For many years, block storage operated on 512-byte physical sectors. To improve storage density and error correction efficiency, the storage industry established the Advanced Format (AF) standard:

• 4Kn (4K Native): The drive physically reads, writes, and addresses blocks in native 4096-byte sectors.
• 512e (512 Emulation): The drive controller translates 512-byte logical requests into 4096-byte physical blocks. If a partition starts at a non-aligned sector, every 512-byte write forces an expensive Read-Modify-Write (RMW) operation across two physical 4K sectors.

3. Solid-State Storage & Flash Translation Layers (FTL)

Solid-state drives (SSDs) and PCIe NVMe devices store data in NAND Flash memory organized into Pages (4KB to 16KB) and Erase Blocks (1MB to 24MB, varying by NAND generation and TLC/QLC technology):

• NAND flash can read and write in pages, but erases can only be performed in entire erase blocks.
• The onboard Flash Translation Layer (FTL) manages wear leveling, garbage collection, and bad block mapping.
• Aligning all partition boundaries to exact 1 MiB (2048-sector) boundaries ensures that partition I/O aligns with internal erase blocks, maximizing performance and prolonging drive endurance.

Partitioning tools like fdisk and gdisk handle this alignment automatically (the fdisk walkthrough demonstrates it in practice). The FTL also benefits from periodic TRIM commands, which inform the controller about freed blocks; see TRIM & discard for configuration. You can measure the performance impact of alignment with the tools in the disk benchmarking guide.