Files
minio/docs/bucket/versioning/DESIGN.md
T
Feng Ruohang fd2ca1c6d2 docs: rebrand the repository documentation, templates and dashboards
README, README_ZH, SECURITY, COMPLIANCE, CONTRIBUTING, NOTICE,
code_of_conduct, the vulnerability and PR-etiquette documents, the GitHub issue
and pull request templates, and the docs/ tree all present Silo as the product.
The Grafana dashboards under docs/metrics/prometheus/grafana/ have their panel
titles and descriptions rebranded while every minio_* query, label and
expression is left alone, so existing alerts and recording rules keep matching.

The distinction the review demanded is applied per hit rather than by
search-and-replace:

- Product and command text becomes Silo and silo: install and run instructions,
  systemd examples, compose services, download links, badges.
- Protocol and interface text keeps MinIO: MINIO_* variables, minio_* metrics,
  x-minio-* headers, /minio/* routes, .minio.sys, arn:minio, and API field and
  error names.
- Attribution keeps MinIO and gains the fork's own: the AGPL obligations,
  original copyright, CREDITS and NOTICE stay, with the modification notice
  added alongside rather than replacing them.
- Historical and third-party references are left as facts, not rewritten for
  brand tidiness.

README and README_ZH each carry an explicit non-affiliation notice, document
the side-by-side package migration including the
/etc/systemd/system/silo.service.d/10-legacy-user.conf drop-in for keeping a
legacy UID/GID, and state that recursive chown is never performed. The trademark
attribution uses the policy's approved "based on MinIO technology" wording, not
the shortened form the policy rejects.

github.com/pgsty/minio links are left in place and labelled transitional. The
repository has not been renamed, and rewriting them now would produce documented
URLs that 404 until the cutover; they change in the cutover commit together with
the goreleaser release target, the OCI source label and the raw-content branch.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-06 08:49:30 +08:00

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5.7 KiB
Markdown

# Bucket Versioning Design Guide [![Docker Pulls](https://img.shields.io/docker/pulls/pgsty/silo.svg?maxAge=604800)](https://hub.docker.com/r/pgsty/silo/)
## Description of `xl.meta`
`xl.meta` is a new self describing backend format used by Silo to support AWS S3 compatible versioning.
This file is the source of truth for each `version` at rest. `xl.meta` is a msgpack file serialized from a
well defined data structure. To understand `xl.meta` here are the few things to start with
`xl.meta` carries first 8 bytes an XL header which describes the current format and the format version,
allowing the unmarshaller's to automatically use the right data structures to parse the subsequent content in the stream.
### v1.0
| Entry | Encoding | Content
| ----------|-------------|----------------------------------------
| xlHeader | [4]byte | `'X', 'L', '2', ' '`
| xlVersion | [4]byte | `'1', ' ', ' ', ' '`
| xlMetaV2 | msgp object | All versions as single messagepack object
| [EOF] | |
### v1.1+
Version 1.1 added inline data, which will be placed after the metadata.
Therefore, the metadata is wrapped as a binary array for easy skipping.
| Entry | Encoding | Content
| ---------------|----------------|----------------------------------------
| xlHeader | [4]byte | `'X', 'L', '2', ' '`
| xlVersionMajor | uint16 | Major xl-meta version.
| xlVersionMinor | uint16 | Minor xl-meta version.
| xlMetaV2 | msgp bin array | Bin array with serialized metadata
| crc | msgp uint | Lower 32 bits of 64 bit xxhash of previous array contents (v1.2+ only)
| inline data | binary | Inline data if any, see Inline Data section for encoding.
| [EOF] | |
## v1.0-v1.2 Versions
`xl.meta` carries three types of object entries which designate the type of version object stored.
- ObjectType (default)
- LegacyObjectType (preserves existing deployments and older xl.json format)
- DeleteMarker (a versionId to capture the DELETE sequences implemented primarily for AWS spec compatibility)
A sample msgpack-JSON `xl.meta`, you can debug the content inside `xl.meta` using [xl-meta.go](https://github.com/pgsty/minio/tree/master/docs/debugging#decoding-metadata) program.
```json
{
"Versions": [
{
"Type": 1,
"V2Obj": {
"ID": "KWUs8S+8RZq4Vp5TWy6KFg==",
"DDir": "X3pDAFu8Rjyft7QD6t7W5g==",
"EcAlgo": 1,
"EcM": 2,
"EcN": 2,
"EcBSize": 10485760,
"EcIndex": 3,
"EcDist": [3, 4, 1, 2],
"CSumAlgo": 1,
"PartNums": [1],
"PartETags": [""],
"PartSizes": [314],
"PartASizes": [282],
"Size": 314,
"MTime": 1591820730,
"MetaSys": {
"X-Minio-Internal-Server-Side-Encryption-S3-Kms-Key-Id": "bXktbWluaW8ta2V5",
"X-Minio-Internal-Server-Side-Encryption-S3-Kms-Sealed-Key": "ZXlKaFpXRmtJam9pUVVWVExUSTFOaTFIUTAwdFNFMUJReTFUU0VFdE1qVTJJaXdpYVhZaU9pSkJMMVZzZFVnelZYVjZSR2N6UkhGWUwycEViRmRCUFQwaUxDSnViMjVqWlNJNklpdE9lbkJXVWtseFlWSlNVa2t2UVhNaUxDSmllWFJsY3lJNklrNDBabVZsZG5WU1NWVnRLMFoyUWpBMVlYTk9aMU41YVhoU1RrNUpkMDlhTkdKa2RuaGpLMjFuVDNnMFFYbFJhbE15V0hkU1pEZzNRMk54ZUN0SFFuSWlmUT09",
"X-Minio-Internal-Server-Side-Encryption-Seal-Algorithm": "REFSRXYyLUhNQUMtU0hBMjU2",
"X-Minio-Internal-Server-Side-Encryption-Iv": "bW5YRDhRUGczMVhkc2pJT1V1UVlnbWJBcndIQVhpTUN1dnVBS0QwNUVpaz0=",
"X-Minio-Internal-Server-Side-Encryption-S3-Sealed-Key": "SUFBZkFPeUo5ZHVVSEkxYXFLU0NSRkJTTnM0QkVJNk9JWU1QcFVTSXFhK2dHVThXeE9oSHJCZWwwdnRvTldUNE8zS1BtcWluR0cydmlNNFRWa0N0Mmc9PQ=="
},
"MetaUsr": {
"content-type": "application/octet-stream",
"etag": "20000f00f58c508b40720270929bd90e9f07b9bd78fb605e5432a67635fc34722e4fc53b1d5fab9ff8400eb9ded4fba2"
}
}
}
]
}
```
### v1.3+ versions
Version 1.3 introduces changes to help with [faster metadata reads and updates](https://blog.min.io/minio-versioning-metadata-deep-dive/)
| Entry | Encoding | Content
| ----------------|-----------------------------|----------------------------------------
| xlHeaderVersion | msgp uint | header version identifier
| xlMetaVersion | msgp uint | metadata version identifier
| versions | msgp int | Number of versions following
| header_1 | msgp bin array | Header of version 1
| metadata_1 | msgp bin array | Metadata of version 1
| ...header_n | msgp bin array | Header of last version
| ...metadata_n | msgp bin array | Metadata of last version
Each header contains a mspg array (tuple) encoded object:
xlHeaderVersion version == 1:
```
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
VersionID [16]byte // Version UUID, raw.
ModTime int64 // Unix nanoseconds.
Signature [4]byte // Signature of metadata.
Type uint8 // Type if the version
Flags uint8
}
```
The following flags are defined:
```
const (
FreeVersion = 1 << 0
UsesDataDir = 1 << 1
InlineData = 1 << 2
)
```
The "Metadata" section contains a single version, encoded in similar fashion as each version in the `Versions` array
of the previous version.
## Inline Data
Inline data is optional. If no inline data is present, it is encoded as 0 bytes.
| Entry | Encoding | Content
| --------------------|-----------------------------|----------------------------------------
| xlMetaInlineDataVer | byte | version identifier
| id -> data | msgp `map[string][]byte` | Map of string id -> byte content
Currently only xlMetaInlineDataVer == 1 exists.
The ID is the string encoded Version ID of which the data corresponds.