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title: ''
labels: community, triage
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---

## NOTE
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<!--- Provide a general summary of the issue in the Title above -->

## Expected Behavior
<!--- If you're describing a bug, tell us what should happen -->

// and heavily modified for MinIO's internal needs.

package handlers

import (
	"net"
	"net/http"
	"regexp"
	"strings"
)

var (
	// De-facto standard header keys.
	xForwardedFor    = http.CanonicalHeaderKey("X-Forwarded-For")
	xForwardedHost   = http.CanonicalHeaderKey("X-Forwarded-Host")
	xForwardedPort   = http.CanonicalHeaderKey("X-Forwarded-Port")

// This function currently supports
// - SIPMOD
func sipHashMod(key string, cardinality int, id [16]byte) int {
	if cardinality <= 0 {
		return -1
	}
	// use the faster version as per siphash docs
	// https://github.com/dchest/siphash#usage
	k0, k1 := binary.LittleEndian.Uint64(id[0:8]), binary.LittleEndian.Uint64(id[8:16])
	sum64 := siphash.Hash(k0, k1, []byte(key))

		// xl.meta has "inlined data" we prefer writing O_DIRECT and then doing
		// fdatasync() at the end instead of opening the file with O_DSYNC.
		//
		// This is an optimization mainly to ensure faster I/O.
		if len(b) > xioutil.DirectioAlignSize {
			r := bytes.NewReader(b)
			return s.writeAllDirect(ctx, filePath, r.Size(), r, flags, skipParent)
		}
		w, err = s.openFileSync(filePath, flags, skipParent)

- Already compressed objects are not fit for compression since they do not have compressible patterns.
Such objects do not produce efficient [`LZ compression`](https://en.wikipedia.org/wiki/LZ77_and_LZ78)
which is a fitness factor for a lossless data compression.

Pre-compressed input typically compresses in excess of 2GiB/s per core,
so performance impact should be minimal even if precompressed data is re-compressed.

- In this algorithm, we also make sure that we spread the drives out evenly. MinIO server expands ellipses passed as arguments. Here is a sample expansion to demonstrate the process.

mapreduce.reduce.shuffle.input.buffer.percent=0.9 # Min % buffer in RAM
mapreduce.reduce.shuffle.merge.percent=0.9 # Minimum % merges in RAM
mapreduce.reduce.speculative=false # Disable speculation for reducing
mapreduce.task.io.sort.factor=999 # Threshold before writing to disk
mapreduce.task.sort.spill.percent=0.9 # Minimum % before spilling to disk
```

command: [ "/bin/sh", "-ce", "/usr/bin/docker-entrypoint.sh minio -S {{ .Values.certsPath }} server --address :{{ .Values.minioAPIPort }} --console-address :{{ .Values.minioConsolePort }} {{- range $i := until $zoneCount }}{{ $factor := mul $i $nodeCount }}{{ $endIndex := add $factor $nodeCount }}{{ $beginIndex := mul $i $nodeCount }} {{ $scheme }}://{{ template `minio.fullname` $ }}-{{ `{` }}{{ $beginIndex }}...{{ sub $endIndex 1 }}{{ `}`}}.{{ template `minio.fullname` $ }}-svc.{{ $.Release.Namespace...

image: {{ .Values.image.repository }}:{{ .Values.image.tag }} imagePullPolicy: {{ .Values.image.pullPolicy }} command: [ "/bin/sh", "-ce", "/usr/bin/docker-entrypoint.sh minio server {{- range $i := until $poolCount }}{{ $factor := mul $i $nodeCount }}{{ $endIndex := add $factor $nodeCount }}{{ $beginIndex := mul $i $nodeCount }} {{ $scheme }}://{{ template `minio.fullname` $ }}-{{ `{` }}{{ $beginIndex }}...{{ sub $endIndex 1 }}{{ `}`}}.{{ template `minio.fullname` $ }}-svc.{{ $.Release.Namespace...

image: {{ .Values.image.repository }}:{{ .Values.image.tag }} imagePullPolicy: {{ .Values.image.pullPolicy }} command: [ "/bin/sh", "-ce", "/usr/bin/docker-entrypoint.sh minio server {{- range $i := until $poolCount }}{{ $factor := mul $i $nodeCount }}{{ $endIndex := add $factor $nodeCount }}{{ $beginIndex := mul $i $nodeCount }} {{ $scheme }}://{{ template `minio.fullname` $ }}-{{ `{` }}{{ $beginIndex }}...{{ sub $endIndex 1 }}{{ `}`}}.{{ template `minio.fullname` $ }}-svc.{{ $.Release.Namespace...