backup-strategy

Backup Strategy Design

Overview

Skills in 3-2-1 strategy, backup verification, and retention policy design.

3-2-1 Backup Strategy

Core Principles

3 - 至少保留 3 份数据副本
2 - 存储在 2 种不同介质上
1 - 至少 1 份异地存储

Extended 3-2-1-1-0: 3 copies 2 types of media 1 offsite copy 1 offline/immutable copy 0 errors (verified)

### 实施示例
```bash
# 本地备份（副本 1）
tar -czvf /backup/local/data_$(date +%Y%m%d).tar.gz /data

# NAS 备份（副本 2，不同介质）
rsync -avz /backup/local/ nas:/backup/

# 云备份（副本 3，异地）
aws s3 sync /backup/local/ s3://backup-bucket/

Backup Types

Full Backup

# 每周完整备份
tar -czvf /backup/full_$(date +%Y%m%d).tar.gz /data

Incremental Backup

# 基于时间戳
tar -czvf /backup/incr_$(date +%Y%m%d).tar.gz \
    --newer-mtime="1 day ago" /data

# 基于快照文件
tar -czvf /backup/incr.tar.gz -g /backup/snapshot.snar /data

Differential Backup

# 基于完整备份时间
tar -czvf /backup/diff_$(date +%Y%m%d).tar.gz \
    --newer-mtime="$(cat /backup/last_full_date)" /data

Retention Policy

GFS Policy

# Grandfather-Father-Son
# 日备份：保留 7 天
# 周备份：保留 4 周
# 月备份：保留 12 个月
# 年备份：保留 7 年

#!/bin/bash
BACKUP_DIR="/backup"
DATE=$(date +%Y%m%d)
DOW=$(date +%u)  # 1-7
DOM=$(date +%d)  # 01-31

# 日备份
tar -czvf ${BACKUP_DIR}/daily/backup_${DATE}.tar.gz /data

# 周备份（周日）
if [ "$DOW" -eq 7 ]; then
    cp ${BACKUP_DIR}/daily/backup_${DATE}.tar.gz ${BACKUP_DIR}/weekly/
fi

# 月备份（1号）
if [ "$DOM" -eq "01" ]; then
    cp ${BACKUP_DIR}/daily/backup_${DATE}.tar.gz ${BACKUP_DIR}/monthly/
fi

# 清理
find ${BACKUP_DIR}/daily -mtime +7 -delete
find ${BACKUP_DIR}/weekly -mtime +28 -delete
find ${BACKUP_DIR}/monthly -mtime +365 -delete

Rolling Retention

#!/bin/bash
# 保留最近 N 个备份
BACKUP_DIR="/backup"
KEEP=10

ls -1t ${BACKUP_DIR}/*.tar.gz | tail -n +$((KEEP+1)) | xargs -r rm

Backup Verification

Integrity Check

# 校验和验证
md5sum backup.tar.gz > backup.md5
md5sum -c backup.md5

# tar 测试
tar -tzvf backup.tar.gz > /dev/null

# gzip 测试
gzip -t backup.tar.gz

Restore Test

#!/bin/bash
# 定期恢复测试
TEST_DIR="/tmp/restore_test"
mkdir -p $TEST_DIR

# 解压测试
tar -xzvf /backup/latest.tar.gz -C $TEST_DIR

# 验证文件数量
ORIG_COUNT=$(find /data -type f | wc -l)
REST_COUNT=$(find $TEST_DIR -type f | wc -l)

if [ "$ORIG_COUNT" -eq "$REST_COUNT" ]; then
    echo "验证通过"
else
    echo "验证失败：文件数量不匹配"
fi

rm -rf $TEST_DIR

Common Scenarios

Scenario 1: Enterprise Backup Solution

#!/bin/bash
# 综合备份脚本
CONFIG="/etc/backup/config"
LOG="/var/log/backup.log"

log() { echo "$(date '+%Y-%m-%d %H:%M:%S') $1" >> $LOG; }

# 数据库备份
log "开始数据库备份"
mysqldump --all-databases | gzip > /backup/db_$(date +%Y%m%d).sql.gz

# 文件备份
log "开始文件备份"
tar -czvf /backup/files_$(date +%Y%m%d).tar.gz /data

# 同步到 NAS
log "同步到 NAS"
rsync -avz /backup/ nas:/backup/

# 上传到云
log "上传到云存储"
aws s3 sync /backup/ s3://backup-bucket/

# 验证
log "验证备份"
gzip -t /backup/*.gz

# 清理
log "清理旧备份"
find /backup -mtime +7 -delete

log "备份完成"

Scenario 2: Backup Monitoring

#!/bin/bash
# 检查备份状态
BACKUP_DIR="/backup"
MAX_AGE=86400  # 24小时

LATEST=$(ls -1t ${BACKUP_DIR}/*.tar.gz 2>/dev/null | head -1)

if [ -z "$LATEST" ]; then
    echo "CRITICAL: 无备份文件"
    exit 2
fi

AGE=$(($(date +%s) - $(stat -c %Y "$LATEST")))

if [ $AGE -gt $MAX_AGE ]; then
    echo "WARNING: 备份超过 24 小时"
    exit 1
fi

echo "OK: 最新备份 $(basename $LATEST)"
exit 0

Strategy Comparison

Strategy	Storage Space	Recovery Speed	Complexity
Full	High	Fast	Low
Incremental	Low	Slow	High
Differential	Medium	Medium	Medium
GFS	Medium	Medium	Medium

Best Practices

1. 自动化备份，避免人工遗漏
2. 定期验证备份可恢复性
3. 加密敏感数据备份
4. 监控备份状态和空间
5. 文档化恢复流程
6. 定期演练恢复过程