軟件raid 5的實現
????raid 5 是一種存儲性能、數據安全和存儲成本兼顧的存儲解決方案。 raid 5可以理解為是raid 0和raid 1的折中方案。raid 5可以為系統提供數據安全保障，但保障程度要比mirror低而磁盤空間利用率要比mirror高。raid 5具有和raid 0相近似的數據讀取速度，只是多了一個奇偶校驗信息，寫入數據的速度比對單個磁盤進行寫入操作稍慢。同時由于多個數據對應一個奇偶校驗信息，raid 5的磁盤空間利用率要比raid 1高，存儲成本相對較低，是目前運用較多的一種解決方案
1 分區
這里使用/dev/sda8、/dev/sda9兩分區和/dev/sdb、/dev/sdc兩個硬盤。
注意：記得把分區的ID 改為fd
2創建raid 5
mdadm?-C?/dev/md5?-a?yes?-l?5?-n?3?-x?1?/dev/sdd1?/dev/sde1?/dev/sdf?/dev/sdb2
[root@centos7?~]#?mdadm?-C?/dev/md5?-a?yes?-l?5?-n?3?-x?1?/dev/sda8?/dev/sda9?/dev/sdb?/dev/sdc mdadm:?Defaulting?to?version?1.2?metadata mdadm:?array?/dev/md5?started.
-C 創建模式
????-n #：使用#個快設備來創建次RAID
????-l #：指明要創建的RAID 的級別
????-a{yes|no}：自動創建目標RAID設備的設備文件
????-c CHUNK_SIZE：指明塊大小
????-x #： 為指定備用磁盤個數，放在最后的默認為備用磁盤
3 創建文件系統
[root@centos7?~]#?mkfs.ext4?/dev/md5
4 掛載
（1）創建掛載目錄
[root@centos7?~]#?mkdir?/mnt/raid5
（2）掛載
[root@centos7?~]#?mount?/dev/md5?/mnt/raid5
5 生成配置文件
[root@centos7?~]#?cat?/etc/mdadm.conf ARRAY?/dev/md5?metadata=1.2?spares=1?name=centos7.3.loacl:5?UUID=5ec4115c:ab1e25c8:ff36d8a2:74f6fd8a
查看md的狀態
[root@centos7?~]#?cat?/proc/mdstat Personalities?:?[raid0]?[raid6]?[raid5]?[raid4] md5?:?active?raid5?sdb[4]?sdc[3](S)?sda9[1]?sda8[0] 2095104?blocks?super?1.2?level?5,?512k?chunk,?algorithm?2?[3/3]?[UUU]
查看raid的詳細信息
[root@centos7?~]#?mdadm?-D?/dev/md5 /dev/md5: Version?:?1.2 Creation?Time?:?Tue?Apr?25?14:38:54?2017 Raid?Level?:?raid5 Array?Size?:?2095104?(2046.00?MiB?2145.39?MB) Used?Dev?Size?:?1047552?(1023.00?MiB?1072.69?MB) Raid?Devices?:?3 Total?Devices?:?4 Persistence?:?Superblock?is?persistent Update?Time?:?Tue?Apr?25?14:50:08?2017 State?:?clean Active?Devices?:?3 Working?Devices?:?4 Failed?Devices?:?0 Spare?Devices?:?1 Layout?:?left-symmetric Chunk?Size?:?512K Name?:?centos7.3.loacl:5?(local?to?host?centos7.3.loacl) UUID?:?5ec4115c:ab1e25c8:ff36d8a2:74f6fd8a Events?:?18 Number?Major?Minor?RaidDevice?State 0?8?8?0?active?sync?/dev/sda8 1?8?9?1?active?sync?/dev/sda9 4?8?16?2?active?sync?/dev/sdb 3?8?32?-?spare?/dev/sdc
可以看到復合預期，三個活動設備，一個空閑（備用）設備
6 禁用和啟用
umount?/mnt/raid0 mdadm?-S?/dev/md0 mdadm?-A?/dev/md0
（1）停用raid
[root@centos7?~]#?umount?/mnt/raid5 [root@centos7?~]#?mdadm?-S?/dev/md5 mdadm:?stopped?/dev/md5
檢查一下，可以看到已經停止成功
[root@centos7?~]#?mdadm?-D?/dev/md5 mdadm:?cannot?open?/dev/md5:?No?such?file?or?directory
（2）啟用raid設備
[root@centos7?~]#?mdadm?-A?/dev/md5 mdadm:?/dev/md5?has?been?started?with?3?drives?and?1?spare.
再來檢查一下，發現已經成功啟動
[root@centos7?~]#?cat?/proc/mdstat Personalities?:?[raid0]?[raid6]?[raid5]?[raid4] md5?:?active?raid5?sda8[0]?sdc[3](S)?sdb[4]?sda9[1] 2095104?blocks?super?1.2?level?5,?512k?chunk,?algorithm?2?[3/3]?[UUU]
7 模擬/dev/sdc損壞
[root@centos7?~]#?mdadm?/dev/md5?-f?/dev/sdc mdadm:?set?/dev/sdc?faulty?in?/dev/md5
8 移除/dev/sdc
[root@centos7?~]#?mdadm?/dev/md5?-r?/dev/sdc mdadm:?hot?removed?/dev/sdc?from?/dev/md5 [root@centos7?~]#?mdadm?-D?/dev/md5 /dev/md5: [……] Active?Devices?:?3 Working?Devices?:?3 Failed?Devices?:?0 Spare?Devices?:?0 [……] Number?Major?Minor?RaidDevice?State 0?8?8?0?active?sync?/dev/sda8 1?8?9?1?active?sync?/dev/sda9 4?8?16?2?active?sync?/dev/sdb 可以看到已經移除成功。
再來看下磁盤情況
[root@centos7?~]#?lsblk NAME?MAJ:MIN?RM?SIZE?RO?TYPE?MOUNTPOINT fd0?2:0?1?4K?0?disk sda?8:0?0?20G?0?disk [……] ├─sda8?8:8?0?1G?0?part │?└─md5?9:5?0?2G?0?raid5 └─sda9?8:9?0?1G?0?part └─md5?9:5?0?2G?0?raid5 sdb?8:16?0?1G?0?disk └─md5?9:5?0?2G?0?raid5 sdc?8:32?0?1G?0?disk sr0?11:0?1?7.7G?0?rom
可以看到/dev/sdc已經不屬于md5陣列
9添加到raid成員
[root@centos7?~]#?mdadm?/dev/md5?-a?/dev/sdc mdadm:?added?/dev/sdc
[root@centos7?~]#?mdadm?-D?/dev/md5 /dev/md5: [……] Raid?Devices?:?3 Total?Devices?:?4 Active?Devices?:?3 Working?Devices?:?4 [……] Number?Major?Minor?RaidDevice?State 0?8?8?0?active?sync?/dev/sda8 1?8?9?1?active?sync?/dev/sda9 4?8?16?2?active?sync?/dev/sdb 3?8?32?-?spare?/dev/sdc
可以看到添加成功
10 增加raid成員數量從3變為4個
這里添加設備/dev/sdd到陣列
[root@centos7?~]#?mdadm?-G?/dev/md5?-n?4?-a?/dev/sdd mdadm:?added?/dev/sdd mdadm:?Need?to?backup?3072K?of?critical?section..
檢查文件系統完整性
[root@centos7?~]#?e2fsck?-f?/dev/md5 e2fsck?1.42.9?(28-Dec-2013) Pass?1:?Checking?inodes,?blocks,?and?sizes Pass?2:?Checking?directory?structure Pass?3:?Checking?directory?connectivity Pass?4:?Checking?reference?counts Pass?5:?Checking?group?summary?information /dev/md5:?11/131072?files?(0.0%?non-contiguous),?17964/523776?blocks
同步文件系統
[root@centos7?~]#?resize2fs?/dev/md5 resize2fs?1.42.9?(28-Dec-2013) Resizing?the?filesystem?on?/dev/md5?to?785664?(4k)?blocks. The?filesystem?on?/dev/md5?is?now?785664?blocks?long.
再來查看/dev/md5陣列情況
[root@centos7?~]#?mdadm?-D?/dev/md5 /dev/md5: Version?:?1.2 Creation?Time?:?Tue?Apr?25?14:38:54?2017 Raid?Level?:?raid5 Array?Size?:?3142656?(3.00?GiB?3.22?GB) Used?Dev?Size?:?1047552?(1023.00?MiB?1072.69?MB) Raid?Devices?:?4 Total?Devices?:?5 Persistence?:?Superblock?is?persistent Update?Time?:?Tue?Apr?25?15:13:32?2017 State?:?clean Active?Devices?:?4 Working?Devices?:?5 Failed?Devices?:?0 Spare?Devices?:?1? Layout?:?left-symmetric Chunk?Size?:?512K Name?:?centos7.3.loacl:5?(local?to?host?centos7.3.loacl) UUID?:?5ec4115c:ab1e25c8:ff36d8a2:74f6fd8a Events?:?47 Number?Major?Minor?RaidDevice?State 0?8?8?0?active?sync?/dev/sda8 1?8?9?1?active?sync?/dev/sda9 4?8?16?2?active?sync?/dev/sdb 5?8?48?3?active?sync?/dev/sdd 3?8?32?-?spare?/dev/sdc
? 版權聲明
文章版權歸作者所有，未經允許請勿轉載。
THE END
