磁盘管理之软RAID
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1、RAID概述
RAID，Redundant Arrays of Inexpensive（Independent）Disks的简称，独立磁盘冗余阵列，简称磁盘阵列。简单来说，RAID是把多个硬盘组合成为一个逻辑扇区，因此，操作系统只会把它当作一个硬盘，经常被用在服务器电脑上。不同的RAID实现的功能也是不尽相同的，或增强处理速度，或增强容错能力，当然，更有甚者，是可以兼备这个特性的。
2、RAID分类
<1>RAID0
<2>RAID1
<3>RAID4
<4>RAID5
<5>RAID01
<6>RAID10
3、经典RAID5的实现
如果只是用作测试的话，软RAID可以在一块硬盘的不同分区上实现，此处用不同的硬盘实现
<1>添加五块硬盘，四块做成RAID阵列，一块做spare硬盘
<2>创建文件系统，并调整分区类型为fd
[[email protected]~]#fdisk /dev/sdb Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): t # 调整分区类型 Selected partition 1 Hex code (type L to list all codes): fd # 选择fd Changed type of partition ‘Linux‘ to ‘Linux raid autodetect‘ Command (m for help): w # 存盘退出 The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
<3>创建RAID设备
[[email protected]~]#mdadm -C /dev/md0 -a yes -l 5 -n 4 -x 1 /dev/sd{b,c,d,e,f}1 mdadm: /dev/sdb1 appears to contain an ext2fs file system size=2097152K mtime=Thu Jan 1 08:00:00 1970 mdadm: /dev/sde1 appears to contain an ext2fs file system size=2097152K mtime=Mon Aug 29 21:32:01 2016 Continue creating array? y # 确定创建 mdadm: Defaulting to version 1.2 metadata mdadm: array /dev/md0 started. # 创建完成并启动
<4>查看创建进度
[[email protected]/mnt]#cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid5 sde1[5] sdf1[4](S) sdd1[2] sdc1[1] sdb1[0] 6285312 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU] # RAID5创建完成，正式启动 unused devices: <none>
<5>查看RAID配置
[[email protected]~]#mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Tue Aug 30 15:38:04 2016 Raid Level : raid5 # RAID级别 Array Size : 6285312 (5.99 GiB 6.44 GB) # 阵列大小，使用率为n-1/n Used Dev Size : 2095104 (2046.34 MiB 2145.39 MB) # 备用的磁盘空间大小 Raid Devices : 4 Total Devices : 5 Persistence : Superblock is persistent Update Time : Tue Aug 30 15:38:14 2016 State : clean Active Devices : 4 # RAID工作状况 Working Devices : 5 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 512K # Chunk默认大小 Name : localhost.localdomain:0 (local to host localhost.localdomain) UUID : fe6313e4:bc14f451:01602e5e:13820d53 Events : 18 Number Major Minor RaidDevice State 0 8 17 0 active sync /dev/sdb1 1 8 33 1 active sync /dev/sdc1 2 8 49 2 active sync /dev/sdd1 5 8 65 3 active sync /dev/sde1 4 8 81 - spare /dev/sdf1 # 备用盘
<6>为RAID5创建文件系统
[[email protected]/mnt]#mkfs.ext4 /dev/md0 mke2fs 1.42.9 (28-Dec-2013) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=128 blocks, Stripe width=384 blocks 393216 inodes, 1571328 blocks ... # 文件系统创建成功
<7>挂载RAID
# 创建挂载点 [[email protected]~]#mkdir /mnt/raid # 编辑/etc/fstab [[email protected]~]#vim /etc/fstab ... UUID="24adec89-2933-47e3-b824-11e25ef679cf" /mnt/raid ext4 defaults 0 0 ... # 挂载 [[email protected]~]#mount -a # 查看挂载 [[email protected]~]#mount ... /dev/md0 on /mnt/raid type ext4 (rw,relatime,seclabel,stripe=384,data=ordered)
<8>创建RAID配置文件
[[email protected]~]#mdadm -Ds /dev/md0 > /etc/mdadm.conf [[email protected]~]#cat /etc/mdadm.conf ARRAY /dev/md0 metadata=1.2 spares=1 name=localhost.localdomain:0 UUID=fe6313e4:bc14f451:01602e5e:13820d53
<9>测试
[[email protected]~]#cp /etc/* /mnt/raid/ -r # 数据已通过挂载点存储在RAID5上 [[email protected]~]#cat /mnt/raid/issue \S Kernel \r on an \m
<9>模拟损坏一块磁盘
# 模拟损坏 [[email protected]~]#mdadm /dev/md0 -f /dev/sdb1 mdadm: set /dev/sdb1 faulty in /dev/md0 # 已损坏 # 查看RAID运行状况 [[email protected]~]#mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Tue Aug 30 15:38:04 2016 Raid Level : raid5 Array Size : 6285312 (5.99 GiB 6.44 GB) Used Dev Size : 2095104 (2046.34 MiB 2145.39 MB) Raid Devices : 4 Total Devices : 5 Persistence : Superblock is persistent Update Time : Tue Aug 30 16:25:52 2016 State : clean, degraded, recovering Active Devices : 3 Working Devices : 4 Failed Devices : 1 Spare Devices : 1 Layout : left-symmetric Chunk Size : 512K Rebuild Status : 57% complete # 进度 Name : localhost.localdomain:0 (local to host localhost.localdomain) UUID : fe6313e4:bc14f451:01602e5e:13820d53 Events : 29 Number Major Minor RaidDevice State 4 8 81 0 spare rebuilding /dev/sdf1 # 正在修复中 1 8 33 1 active sync /dev/sdc1 2 8 49 2 active sync /dev/sdd1 5 8 65 3 active sync /dev/sde1 0 8 17 - faulty /dev/sdb1 # faulty状态 # 查看数据 [[email protected]~]#cat /etc/issue \S Kernel \r on an \m # 数据无损坏
<10>不修复faulty硬盘，再次模拟损坏一块硬盘
# 损坏硬盘 [[email protected]~]#mdadm /dev/md0 -f /dev/sdc1 mdadm: set /dev/sdc1 faulty in /dev/md0 # 查看状态 [[email protected]~]#mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Tue Aug 30 15:38:04 2016 Raid Level : raid5 Array Size : 6285312 (5.99 GiB 6.44 GB) Used Dev Size : 2095104 (2046.34 MiB 2145.39 MB) Raid Devices : 4 Total Devices : 5 Persistence : Superblock is persistent Update Time : Tue Aug 30 16:33:01 2016 State : clean, degraded Active Devices : 3 Working Devices : 3 Failed Devices : 2 Spare Devices : 0 Layout : left-symmetric Chunk Size : 512K # 也没有修复的进度 Name : localhost.localdomain:0 (local to host localhost.localdomain) UUID : fe6313e4:bc14f451:01602e5e:13820d53 Events : 39 Number Major Minor RaidDevice State 4 8 81 0 active sync /dev/sdf1 2 0 0 2 removed # 没有硬盘顶替，显示remove状态 2 8 49 2 active sync /dev/sdd1 5 8 65 3 active sync /dev/sde1 0 8 17 - faulty /dev/sdb1 # 已损坏 1 8 33 - faulty /dev/sdc1 # 已损坏 # 再次查看数据 [[email protected]~]#cat /mnt/raid/issue \S Kernel \r on an \m # 数据无损
<11>依然不修复，再次损坏
# 损坏硬盘 [[email protected]~]#mdadm /dev/md0 -f /dev/sdd1 mdadm: set /dev/sdd1 faulty in /dev/md0 [[email protected]~]#mdadm -D /dev/md0 /dev/md0: Version : 1.2 Creation Time : Tue Aug 30 15:38:04 2016 Raid Level : raid5 Array Size : 6285312 (5.99 GiB 6.44 GB) Used Dev Size : 2095104 (2046.34 MiB 2145.39 MB) Raid Devices : 4 Total Devices : 5 Persistence : Superbloc k is persistent Update Time : Tue Aug 30 16:39:41 2016 State : clean, FAILED Active Devices : 2 Working Devices : 2 Failed Devices : 3 Spare Devices : 0 Layout : left-symmetric Chunk Size : 512K Name : localhost.localdomain:0 (local to host localhost.localdomain) UUID : fe6313e4:bc14f451:01602e5e:13820d53 Events : 41 Number Major Minor RaidDevice State 4 8 81 0 active sync /dev/sdf1 2 0 0 2 removed # 移除 4 0 0 4 removed # 移除 5 8 65 3 active sync /dev/sde1 0 8 17 - faulty /dev/sdb1 # 已损坏 1 8 33 - faulty /dev/sdc1 # 已损坏 2 8 49 - faulty /dev/sdd1 # 已损坏 # RAID5中，已损坏俩块硬盘，校验数据失效，数据全部损坏。 [[email protected]~]#cat /mnt/raid/fstab cat: /mnt/raid/fstab: Input/output error
此时数据已经损坏，不可恢复
RAID支持热插拔技术
<12>在RAID 不损坏之前也是可以增加RAID的磁盘的
[[email protected]~]#mdadm -G /dev/md0 -a -n 5 /dev/sdg1
RAID损坏后，移除RAID
[[email protected]~]#mdadm /dev/md0 -r /dev/sdb1 mdadm: hot removed /dev/sdb1 from /dev/md0
标准的卸载RAID的步骤
<13>取消挂载、停止RAID、删除配置文件
[[email protected]~]#umount /mnt/raid/ [[email protected]~]#mdadm -S /dev/md0 备注----->启用RAID：mdadm -A -s /dev/md5 mdadm: stopped /dev/md0 [[email protected]~]#rm -f /etc/mdadm.conf
<14>移除RAID中的磁盘
<15>删除磁盘上的RAID信息
[[email protected]~]#mdadm --zero-superblock /dev/sdf1 # 一定要先停止，否则报错
本文出自 “LINUX_Home” 博客，请务必保留此出处http://dmwing.blog.51cto.com/11607397/1844494
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