Block to Gibibit

Modern hard drives (2011+) and SSDs use 4,096-byte (4 KiB) physical sectors — known as "Advanced Format" or AF. Legacy drives used 512-byte sectors. Filesystems (NTFS, ext4, APFS) typically use 4 KiB logical block sizes to match physical sectors, which avoids the performance penalty of misaligned writes. Enterprise SSDs may use larger block sizes (16 KiB or more) for better parallelism.

Cloud block storage services (AWS EBS, Azure Managed Disks, GCP Persistent Disk) use I/O block sizes typically of 4 KiB or 16 KiB. Performance is measured in IOPS (I/O operations per second) and throughput (MB/s) — both depend on block size. A throughput-optimized workload (sequential video) benefits from large blocks; an IOPS-optimized workload (database random reads) uses small blocks.

Filesystems allocate disk space in whole blocks. On a system with 4 KiB blocks, every file — no matter how small — occupies at least 4,096 bytes. A directory of 10,000 small configuration files (each 100 bytes of content) uses 40 MB of disk space (10,000 × 4,096 bytes) rather than 1 MB (10,000 × 100 bytes). This is called "block slack" or "internal fragmentation".

Disk blocks (filesystem blocks) are typically 512 bytes to 4 KiB. Database blocks (database pages) are the unit of I/O for a database engine — typically 8 KiB (PostgreSQL, SQL Server), 16 KiB (MySQL InnoDB), or 32 KiB (Oracle, configurable). Database blocks usually align to multiples of disk blocks for efficiency. Reading one database page may involve reading 2–8 disk blocks.

RAID stripe size (or chunk size) is the amount of data written to each drive before moving to the next drive in the array — typically 64 KiB to 512 KiB. It should be set to match your workload: sequential large-file workloads benefit from larger stripe sizes; random small-block workloads benefit from stripe sizes closer to the filesystem block size. Mismatched stripe and block sizes cause write amplification and reduce RAID performance.

A gigabit (Gbit) = 10⁹ bits = 1,000,000,000 bits (SI). A gibibit (Gibit) = 2³⁰ bits = 1,073,741,824 bits (IEC binary). The difference is 7.37%. Consumer networking equipment and ISP speed ratings use decimal gigabits; memory and chip designers sometimes use gibibits when binary precision is required.

Virtually all networking equipment — routers, switches, NICs, ISP speed ratings — uses decimal gigabits (Gbit). A "1 Gbps" (gigabit per second) connection means exactly 1,000,000,000 bits per second, not 1,073,741,824 bits per second. Network standards (Ethernet IEEE 802.3) are defined in SI units.

DDR memory bandwidth is calculated from clock speed, bus width, and transfers per clock. A DDR5-4800 module on a 64-bit bus delivers 4,800 MT/s × 64 bits = 307,200 Mbit/s ≈ 292.97 Gibit/s. Engineers use gibibits when verifying that memory throughput matches binary-aligned cache line sizes (typically 512 bits = 64 bytes), ensuring no fractional transfers occur during burst reads.

GPU memory bandwidth is typically quoted in gigabytes per second (GB/s) using SI decimal values — not gibibits. For example, NVIDIA's RTX 4090 has 1,008 GB/s of memory bandwidth (decimal). Some academic papers and IEEE publications convert this to GiB/s or Gibit/s for precision, but consumer GPU marketing universally uses SI decimal units.

Gibibit appears in: IEEE standards documents specifying memory interface speeds, JEDEC memory specifications, some academic networking papers, and storage controller datasheets. Consumer-facing software, marketing materials, and OS interfaces virtually never display gibibits — they show gigabits (networking) or gigabytes (storage). It is primarily a precision engineering unit.