druid/docs/configuration/human-readable-byte.md

id	title
human-readable-byte	Human-readable Byte Configuration Reference

This page documents configuration properties related to bytes.

These properties can be configured through 2 ways:

1. a simple number in bytes
2. a number with a unit suffix

A number in bytes

Given that cache size is 3G, there's a configuration as below

# 3G bytes = 3_000_000_000 bytes
druid.cache.sizeInBytes=3000000000 

A number with a unit suffix

When you have to put a large number for some configuration as above, it is easy to make a mistake such as extra or missing 0s. Druid supports a better way, a number with a unit suffix.

Given a disk of 1T, the configuration can be

druid.segmentCache.locations=[{"path":"/segment-cache-00","maxSize":"1t"},{"path":"/segment-cache-01","maxSize":"1200g"}]

Note: in above example, both 1t and 1T are acceptable since it's case-insensitive. Also, only integers are valid as the number part. For example, you can't replace 1200g with 1.2t.

Supported Units

In the world of computer, a unit like K is ambiguous. It means 1000 or 1024 in different contexts, for more information please see Here.

To make it clear, the base of units are defined in Druid as below

Unit	Description	Base
K	Kilo Decimal Byte	1_000
M	Mega Decimal Byte	1_000_000
G	Giga Decimal Byte	1_000_000_000
T	Tera Decimal Byte	1_000_000_000_000
P	Peta Decimal Byte	1_000_000_000_000_000
KiB	Kilo Binary Byte	1024
MiB	Mega Binary Byte	1024 * 1024
GiB	Giga Binary Byte	1024 * 1024 * 1024
TiB	Tera Binary Byte	1024 * 1024 * 1024 * 1024
PiB	Peta Binary Byte	1024 * 1024 * 1024 * 1024 * 1024

Unit is case-insensitive. k, kib, KiB, kiB are all acceptable.

Here are two examples

# 1G bytes = 1_000_000_000 bytes
druid.cache.sizeInBytes=1g 

# 256MiB bytes = 256 * 1024 * 1024 bytes
druid.cache.sizeInBytes=256MiB