minio/docs/backend/xl/README.md

Backend format xl.json

// objectPartInfo Info of each part kept in the multipart metadata
// file after CompleteMultipartUpload() is called.
type objectPartInfo struct {
	Number int    `json:"number"`
	Name   string `json:"name"`
	ETag   string `json:"etag"`
	Size   int64  `json:"size"`
}

// checkSumInfo - carries checksums of individual scattered parts per disk.
type checkSumInfo struct {
	Name      string `json:"name"`
	Algorithm string `json:"algorithm"`
	Hash      string `json:"hash"`
}

// erasureInfo - carries erasure coding related information, block
// distribution and checksums.
type erasureInfo struct {
	Algorithm    string         `json:"algorithm"`
	DataBlocks   int            `json:"data"`
	ParityBlocks int            `json:"parity"`
	BlockSize    int64          `json:"blockSize"`
	Index        int            `json:"index"`
	Distribution []int          `json:"distribution"`
	Checksum     []checkSumInfo `json:"checksum,omitempty"`
}

// statInfo - carries stat information of the object.
type statInfo struct {
	Size    int64     `json:"size"`    // Size of the object `xl.json`.
	ModTime time.Time `json:"modTime"` // ModTime of the object `xl.json`.
}

// A xlMetaV1 represents `xl.json` metadata header.
type xlMetaV1 struct {
	Version string   `json:"version"` // Version of the current `xl.json`.
	Format  string   `json:"format"`  // Format of the current `xl.json`.
	Stat    statInfo `json:"stat"`    // Stat of the current object `xl.json`.
	// Erasure coded info for the current object `xl.json`.
	Erasure erasureInfo `json:"erasure"`
	// Minio release tag for current object `xl.json`.
	Minio struct {
		Release string `json:"release"`
	} `json:"minio"`
	// Metadata map for current object `xl.json`.
	Meta map[string]string `json:"meta,omitempty"`
	// Captures all the individual object `xl.json`.
	Parts []objectPartInfo `json:"parts,omitempty"`
}