doc: Change GiB to GB in release-process.md

[BenWestgate]

This will make it consistent with the Welcome GUI and code comments which use "GB" for the m_assumed_blockchain_size and m_assumed_chain_state_size values.

Since they are used as GB values to calculate disk space in GB needed in the GUI, measuring size in GiB here will cause users to run out of space without a graphical warning. The error between units is over 45 GB for the full chain.

This doc is the only place we say they are GiB, and while an 8-10% overhead can account for the unit conversion, we say the overhead was for growth between releases, not abusing the units without conversion.

bitcoin/src/kernel/chainparams.h

Lines 106 to 109 in 4c387cb

	/** Minimum free space (in GB) needed for data directory */
	uint64_t AssumedBlockchainSize() const { return m_assumed_blockchain_size; }
	/** Minimum free space (in GB) needed for data directory when pruned; Does not include prune target*/
	uint64_t AssumedChainStateSize() const { return m_assumed_chain_state_size; }

Here is a 3rd spot where the GiB value is presented to the user as GB:

bitcoin/src/init.cpp

Lines 1696 to 1713 in 4c387cb

	// On first startup, warn on low block storage space
	if (!chainman.m_blockman.m_reindexing && !fReindexChainState && chain_active_height <= 1) {
	uint64_t assumed_chain_bytes{chainparams.AssumedBlockchainSize() * 1024 * 1024 * 1024};
	uint64_t additional_bytes_needed{
	chainman.m_blockman.IsPruneMode() ?
	std::min(chainman.m_blockman.GetPruneTarget(), assumed_chain_bytes) :
	assumed_chain_bytes};
	if (!CheckDiskSpace(args.GetBlocksDirPath(), additional_bytes_needed)) {
	InitWarning(strprintf(_(
	"Disk space for %s may not accommodate the block files. " \
	"Approximately %u GB of data will be stored in this directory."
	),
	fs::quoted(fs::PathToString(args.GetBlocksDirPath())),
	chainparams.AssumedBlockchainSize()
	));
	}
	}

However, it comes right after using the value correctly as GiB (unlike in GUI which uses it as GB). So that may need to be patched to calculate bytes from GB instead of GiB.

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Concept ACK	epiccurious

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[epiccurious]

Concept ACK c04edce.

This assumes the value should be displayed in GB. Is there a benefit to doing the calculation and displaying in GiB instead?

[BenWestgate]

Concept ACK c04edce.

This assumes the value should be displayed in GB. Is there a benefit to doing the calculation and displaying in GiB instead?

Software usually displays large sizes in GB because that's what the operating system and storage manufacturers use.

[sipa]

Software usually displays large sizes in GB because that's what the operating system and storage manufacturers use.

I don't think that's universally true. I believe Apple generally uses GB (meaning 10⁹), Microsoft generally uses GB (meaning 2³⁰), and open-source systems use a mix (sometimes using GiB to mean 2³⁰).

[BenWestgate]

I don't think that's universally true. I believe Apple generally uses GB (meaning 109), Microsoft generally uses GB (meaning 230), and open-source systems use a mix (sometimes using GiB to mean 230).

Good to know. Should the value we display depend on platform then? At the very least I think we should be consistent within the repository or within a file. Currently we do math that adds and subtracts GiB from GB in the GUI welcome screen which will cause issues. bitcoin-core/gui#821

In response to litigation over whether the makers of electronic storage devices must conform to Microsoft Windows' use of a binary definition of "GB" instead of the metric/decimal definition, the United States District Court for the Northern District of California rejected that argument, ruling that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce.'"

To resolve this difficulty, IEC 80000-13 clarifies that a gigabyte (GB) is 10^9 bytes and specifies the term gibibyte (GiB) to denote 2^30 bytes.

[epiccurious]

Should the value we display depend on platform then?

This makes sense to me for the UI, since the average user will be able to compare values to their local environments in the macOS Finder and Windows Explorer applications.

[luke-jr]

This is a duplicate of #29678 (without the accompanying code fixes)