Mebibyte per second to Bit per second

dd uses binary units because Linux filesystems work in binary block sizes (4 KiB, etc.). Drive manufacturers use decimal MB/s because it makes speeds look about 5% higher and aligns with their decimal capacity marketing. A "550 MB/s" SSD shows roughly 524 MiB/s in dd.

Run "dd if=/dev/zero of=testfile bs=1M count=1024 oflag=direct" and it will report write speed in MiB/s. For read speed, use "dd if=testfile of=/dev/null bs=1M". The oflag=direct flag bypasses filesystem cache to measure actual disk performance.

No — 550 MiB/s is about 577 MB/s, and 550 MB/s is about 524 MiB/s. The ~5% difference means an SSD advertised at 550 MB/s will show around 524 MiB/s in Linux tools. It is not a defect or false advertising, just different unit systems measuring the same physical speed.

A RAID 0 stripe of two SATA SSDs gives roughly 1,000–1,100 MiB/s sequential reads. Four NVMe SSDs in RAID 0 can hit 12,000–14,000 MiB/s. RAID 5/6 arrays sacrifice some write speed for redundancy — expect 70–90% of raw stripe performance on writes.

Sequential reads let the drive stream data from contiguous locations, maximising throughput. Random I/O forces the controller to seek different addresses, adding latency per operation. An NVMe SSD might do 7,000 MiB/s sequential but only 50–80 MiB/s random (at 4 KiB block size), because the bottleneck shifts from bandwidth to IOPS.

A bit represents a single binary choice — 0 or 1 — which is the fundamental quantum of digital information. Every larger unit (byte, kilobit, megabit) is just a multiple of bits. You cannot meaningfully subdivide a binary digit, so bps is the floor of data rate measurement.

LoRaWAN IoT sensors, some RFID readers, and legacy serial ports (RS-232 at 300–9600 baud) still deal in raw bps ranges. Satellites communicating with deep-space probes also use very low bps — NASA's Voyager 1 transmits at about 160 bps from interstellar space.

Not exactly. Baud measures symbol changes per second, while bps measures bits per second. If each symbol encodes one bit, they are equal. But modern modems encode multiple bits per symbol — a 2400-baud modem using 16-QAM transmits 9600 bps because each symbol carries 4 bits.

Research suggests human speech carries about 39 bits per second of actual information content, regardless of language. Italian speakers talk faster but convey less information per syllable than Japanese speakers, balancing out to roughly the same bps across all studied languages.

The 56 kbps limit came from the Shannon-Hartley theorem applied to analogue phone lines. The 3.1 kHz bandwidth of a voice telephone channel, combined with its signal-to-noise ratio, creates a theoretical ceiling near 56 kbps. FCC power regulations further capped actual downstream to 53.3 kbps.