Pebibyte to Megabyte

PB (petabyte) = 10¹⁵ bytes = 1,000,000,000,000,000 bytes (SI decimal). PiB (pebibyte) = 2⁵⁰ bytes = 1,125,899,906,842,624 bytes (IEC binary). PiB is 12.59% larger. For a data center purchasing 100 PiB of raw storage, the SI vs IEC confusion would represent approximately 12.59 PB of missing or unexpected capacity.

Cloud providers (AWS, Azure, GCP) operate at exabyte scale but provision and bill individual customers at PiB scale for enterprise storage. Scientific computing facilities like CERN, the Square Kilometer Array telescope project, and US national laboratories store tens to hundreds of PiB. Large video platforms (Netflix, YouTube) store hundreds of PiB of encoded video content.

Using 20 TB drives (a 2024 high-density consumer drive): 1 PiB = 1,125,899,906,842,624 bytes ÷ 20,000,000,000,000 bytes/drive ≈ 56.3 drives. So roughly 57 × 20 TB drives to fill 1 PiB. In a data center using 60-drive storage shelves, one shelf of 60 × 20 TB drives provides about 1.07 PiB of raw capacity.

Magnetic tape (LTO technology) remains the dominant medium for cold storage at PiB scale due to economics and durability. An LTO-9 cartridge holds 18 TB (uncompressed) and costs roughly $100 — about $5.50 per TB, versus $15–20 per TB for HDDs. Tape also consumes zero power when idle, unlike spinning disks. The IBM TS4500 tape library can hold over 40 PiB in a single rack. Major users include CERN, national archives, and film studios — Netflix stores its master copies on tape. Tape's main downside is sequential access: retrieving a specific file can take minutes versus milliseconds for disk.

CERN's Worldwide LHC Computing Grid stores approximately 300–400 PB (petabytes, decimal) of data across distributed sites, with the main Tier-0 facility at CERN holding about 100 PB on disk and 200 PB on tape. The LHC generates roughly 15 PB of data per year from collision events. Future upgrades (High-Luminosity LHC) are projected to increase this to 50–100 PB per year.

A JPEG photo from a modern smartphone is typically 3–8 MB depending on resolution and compression settings. A RAW format photo from a DSLR or mirrorless camera is 20–50 MB per shot. A PNG screenshot at full HD (1920×1080) is about 1–3 MB; a compressed JPEG screenshot may be under 200 kB.

Video data usage depends heavily on quality: SD video uses roughly 700 MB per hour; HD (1080p) uses 1.5–3 GB per hour; 4K uses 7–20 GB per hour. These are byte-based measurements. In terms of bitrate: SD ≈ 1.5 Mbps, HD ≈ 5–8 Mbps, 4K ≈ 15–25 Mbps — where the "b" is bits, requiring division by 8 to convert to MB/s.

Compression algorithms like ZIP, GZIP, and ZSTD find and eliminate redundancy in data. Typical ratios vary dramatically by file type: plain text compresses to 20–30% of original size (a 10 MB log file becomes 2–3 MB); source code compresses to 25–35%; office documents (DOCX, XLSX) are already ZIP-compressed internally, so re-compressing gains little. JPEG, MP3, and H.264 video are already lossy-compressed and typically shrink by less than 5% with ZIP. A 100 MB folder of mixed files typically compresses to 40–60 MB. The key principle: compression removes statistical redundancy, so already-compressed or random data cannot be reduced further.

MB (megabyte) = 1,000,000 bytes (SI decimal). MiB (mebibyte) = 1,048,576 bytes (IEC binary). The difference is about 4.9%. Windows historically displayed storage in binary units but labelled them as "MB" — confusingly. Since Windows Vista, Microsoft has used the binary calculation consistently. macOS switched to SI decimal units in OS X 10.6 Snow Leopard (2009), matching the way hard drive manufacturers measure capacity.

Approximate data consumption per hour: web browsing = 60–100 MB, social media scrolling = 100–300 MB, music streaming (Spotify standard) = 40–50 MB, video calls (Zoom standard quality) = 300–500 MB, YouTube HD = 1,500–3,000 MB. These are rough averages and vary by content, settings, and network conditions.