Gigabit to Block

1 Gbps (gigabit) broadband delivers up to 125 MB/s, which is more than sufficient for most households. It supports dozens of simultaneous 4K streams, fast game downloads, and video conferencing with headroom to spare. The limiting factor is usually the Wi-Fi router (Wi-Fi 5 maxes out around 400–600 Mbps in practice) or the speed of the remote server you're downloading from.

10 Gbps networking is standard in data centers, server interconnects, and high-performance workstations doing large file transfers (video editing, database backups). It is increasingly available in prosumer home networking equipment. At 10 Gbps, a 1 TB file transfer takes about 13 minutes under ideal conditions.

One terabit equals 1,000 gigabits (SI). Terabit-per-second (Tbps) speeds are used in long-haul fiber optic cables and internet backbone infrastructure. A single transatlantic fiber cable typically carries hundreds of terabits per second across many multiplexed channels.

Wi-Fi 5 (802.11ac) delivers up to 3.5 Gbps theoretical, but typically 400–600 Mbps real-world on a single device. Wi-Fi 6 (802.11ax) reaches 9.6 Gbps theoretical and 600–900 Mbps practical per device, with better multi-device handling via OFDMA. Wi-Fi 6E extends the same technology into the uncongested 6 GHz band, improving real-world speeds to 1–2 Gbps. Wi-Fi 7 (802.11be) pushes the theoretical maximum to 46 Gbps using 320 MHz channels and 4096-QAM, with real-world single-device speeds expected around 2–5 Gbps — the first Wi-Fi standard to reliably exceed gigabit in practice.

Modern data centers handle enormous simultaneous traffic between thousands of servers — cloud computing, video streaming, and AI training all require massive internal bandwidth. 100 Gbps links between switches are now standard; 400 Gbps is increasingly deployed for spine connections. At these speeds, a single link can move 50 GB of data per second, keeping pace with NVMe storage arrays and GPU memory transfer rates.

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.