RAID可以大幅度的提高磁盘性能，以及可靠性，这么好的技术怎么能不掌握呢！此篇介绍一些常见RAID，及其在Linux上的软RAID创建方法。
mdadm
- 创建软
RAID
mdadm -C -v /dev/创建的设备名 -l级别 -n数量 添加的磁盘 [-x数量 添加的热备份盘]
-C：创建一个新的阵列--create
-v：显示细节--verbose
-l：设定RAID级别--level=
-n：指定阵列中可用device数目--raid-devices=
-x：指定初始阵列的富余device数目--spare-devices=，空闲盘（热备磁盘）能在工作盘损坏后自动顶替
- 查看详细信息
mdadm -D /dev/设备名
-D：打印一个或多个md device的详细信息--detail
- 查看
RAID的状态
cat /proc/mdstat
- 模拟损坏
mdadm -f /dev/设备名 磁盘
-f：模拟损坏fail
- 移除损坏
mdadm -r /dev/设备名 磁盘
-r：移除remove
- 添加新硬盘作为热备份盘
mdadm -a /dev/设备名 磁盘
-a：添加add
RAID0
RAID0俗称条带，它将两个或多个硬盘组成一个逻辑硬盘，容量是所有硬盘之和，因为是多个硬盘组合成一个，故可并行写操作，写入速度提高，但此方式硬盘数据没有冗余，没有容错，一旦一个物理硬盘损坏，则所有数据均丢失。因而，RAID0适合于对数据量大，但安全性要求不高的场景，比如音像、视频文件的存储等。
实验：RAID0创建，格式化，挂载使用。
1.添加2块20G的硬盘，分区，类型ID为fd。
[root@localhost ~]# fdisk -l | grep raid
/dev/sdb1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdc1 2048 41943039 20970496 fd Linux raid autodetect
2.创建RAID0。
[root@localhost ~]# mdadm -C -v /dev/md0 -l0 -n2 /dev/sd{b,c}1
mdadm: chunk size defaults to 512K
mdadm: Fail create md0 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
3.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid0]
md0 : active raid0 sdc1[1] sdb1[0]
41906176 blocks super 1.2 512k chunks
unused devices: <none>
4.查看RAID0的详细信息。
[root@localhost ~]# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sun Aug 25 15:28:13 2019
Raid Level : raid0
Array Size : 41906176 (39.96 GiB 42.91 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:28:13 2019
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Consistency Policy : none
Name : localhost:0 (local to host localhost)
UUID : 7ff54c57:b99a59da:6b56c6d5:a4576ccf
Events : 0
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
5.格式化。
[root@localhost ~]# mkfs.xfs /dev/md0
meta-data=/dev/md0 isize=512 agcount=16, agsize=654720 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=10475520, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
6.挂载使用。
[root@localhost ~]# mkdir /mnt/md0
[root@localhost ~]# mount /dev/md0 /mnt/md0/
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 17G 1013M 16G 6% /
devtmpfs devtmpfs 901M 0 901M 0% /dev
tmpfs tmpfs 912M 0 912M 0% /dev/shm
tmpfs tmpfs 912M 8.7M 904M 1% /run
tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 143M 872M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
/dev/md0 xfs 40G 33M 40G 1% /mnt/md0
RAID1
RAID1俗称镜像，它最少由两个硬盘组成，且两个硬盘上存储的数据均相同，以实现数据冗余。RAID1读操作速度有所提高，写操作理论上与单硬盘速度一样，但由于数据需要同时写入所有硬盘，实际上稍为下降。容错性是所有组合方式里最好的，只要有一块硬盘正常，则能保持正常工作。但它对硬盘容量的利用率则是最低，只有50%，因而成本也是最高。RAID1适合对数据安全性要求非常高的场景，比如存储数据库数据文件之类。
实验：RAID1创建，格式化，挂载使用，故障模拟，重新添加热备份。
1.添加3块20G的硬盘，分区，类型ID为fd。
[root@localhost ~]# fdisk -l | grep raid
/dev/sdb1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdc1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdd1 2048 41943039 20970496 fd Linux raid autodetect
2.创建RAID1，并添加1个热备份盘。
[root@localhost ~]# mdadm -C -v /dev/md1 -l1 -n2 /dev/sd{b,c}1 -x1 /dev/sdd1
mdadm: Note: this array has metadata at the start and
may not be suitable as a boot device. If you plan to
store '/boot' on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
--metadata=0.90
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md1 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.
3.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdd1[2](S) sdc1[1] sdb1[0]
20953088 blocks super 1.2 [2/2] [UU]
[========>............] resync = 44.6% (9345792/20953088) finish=0.9min speed=203996K/sec
unused devices: <none>
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdd1[2](S) sdc1[1] sdb1[0]
20953088 blocks super 1.2 [2/2] [UU]
unused devices: <none>
4.查看RAID1的详细信息。
[root@localhost ~]# mdadm -D /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Aug 25 15:38:44 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:39:24 2019
State : clean, resyncing
Active Devices : 2
Working Devices : 3
Failed Devices : 0
Spare Devices : 1
Consistency Policy : resync
Resync Status : 40% complete
Name : localhost:1 (local to host localhost)
UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
Events : 6
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
2 8 49 - spare /dev/sdd1
5.格式化。
[root@localhost ~]# mkfs.xfs /dev/md1
meta-data=/dev/md1 isize=512 agcount=4, agsize=1309568 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5238272, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
6.挂载使用。
[root@localhost ~]# mkdir /mnt/md1
[root@localhost ~]# mount /dev/md1 /mnt/md1/
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 17G 1014M 16G 6% /
devtmpfs devtmpfs 901M 0 901M 0% /dev
tmpfs tmpfs 912M 0 912M 0% /dev/shm
tmpfs tmpfs 912M 8.7M 904M 1% /run
tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 143M 872M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
/dev/md1 xfs 20G 33M 20G 1% /mnt/md1
7.创建测试文件。
[root@localhost ~]# touch /mnt/md1/test{1..9}.txt
[root@localhost ~]# ls /mnt/md1/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
8.故障模拟。
[root@localhost ~]# mdadm -f /dev/md1 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md1
9.查看测试文件。
[root@localhost ~]# ls /mnt/md1/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
10.查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdd1[2] sdc1[1] sdb1[0](F)
20953088 blocks super 1.2 [2/1] [_U]
[=====>...............] recovery = 26.7% (5600384/20953088) finish=1.2min speed=200013K/sec
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Aug 25 15:38:44 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:47:57 2019
State : active, degraded, recovering
Active Devices : 1
Working Devices : 2
Failed Devices : 1
Spare Devices : 1
Consistency Policy : resync
Rebuild Status : 17% complete
Name : localhost:1 (local to host localhost)
UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
Events : 22
Number Major Minor RaidDevice State
2 8 49 0 spare rebuilding /dev/sdd1
1 8 33 1 active sync /dev/sdc1
0 8 17 - faulty /dev/sdb1
11.再次查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdd1[2] sdc1[1] sdb1[0](F)
20953088 blocks super 1.2 [2/2] [UU]
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Aug 25 15:38:44 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:49:28 2019
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Consistency Policy : resync
Name : localhost:1 (local to host localhost)
UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
Events : 37
Number Major Minor RaidDevice State
2 8 49 0 active sync /dev/sdd1
1 8 33 1 active sync /dev/sdc1
0 8 17 - faulty /dev/sdb1
12.移除损坏的磁盘
[root@localhost ~]# mdadm -r /dev/md1 /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md1
[root@localhost ~]# mdadm -D /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Aug 25 15:38:44 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:52:57 2019
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Name : localhost:1 (local to host localhost)
UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
Events : 38
Number Major Minor RaidDevice State
2 8 49 0 active sync /dev/sdd1
1 8 33 1 active sync /dev/sdc1
13.重新添加热备份盘。
[root@localhost ~]# mdadm -a /dev/md1 /dev/sdb1
mdadm: added /dev/sdb1
[root@localhost ~]# mdadm -D /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Sun Aug 25 15:38:44 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sun Aug 25 15:53:32 2019
State : active
Active Devices : 2
Working Devices : 3
Failed Devices : 0
Spare Devices : 1
Consistency Policy : resync
Name : localhost:1 (local to host localhost)
UUID : b921e8b3:a18e2fc9:11706ba4:ed633dfd
Events : 39
Number Major Minor RaidDevice State
2 8 49 0 active sync /dev/sdd1
1 8 33 1 active sync /dev/sdc1
3 8 17 - spare /dev/sdb1
RAID5
RAID5最少由三个硬盘组成，它将数据分散存储于阵列中的每个硬盘，并且还伴有一个数据校验位，数据位与校验位通过算法能相互验证，当丢失其中的一位时，RAID控制器能通过算法，利用其它两位数据将丢失的数据进行计算还原。因而RAID5最多能允许一个硬盘损坏，有容错性。RAID5相对于其它的组合方式，在容错与成本方面有一个平衡，因而受到大多数使用者的欢迎。一般的磁盘阵列，最常使用的就是RAID5这种方式。
实验：RAID5创建，格式化，挂载使用，故障模拟，重新添加热备份。
1.添加4块20G的硬盘，分区，类型ID为fd。
[root@localhost ~]# fdisk -l | grep raid
/dev/sdb1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdc1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdd1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sde1 2048 41943039 20970496 fd Linux raid autodetect
2.创建RAID5，并添加1个热备份盘。
[root@localhost ~]# mdadm -C -v /dev/md5 -l5 -n3 /dev/sd[b-d]1 -x1 /dev/sde1
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: size set to 20953088K
mdadm: Fail create md5 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.
3.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdd1[4] sde1[3](S) sdc1[1] sdb1[0]
41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [UU_]
[====>................] recovery = 24.1% (5057340/20953088) finish=1.3min speed=202293K/sec
unused devices: <none>
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdd1[4] sde1[3](S) sdc1[1] sdb1[0]
41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>
4.查看RAID5的详细信息。
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Aug 25 16:13:44 2019
Raid Level : raid5
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:15:29 2019
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:5 (local to host localhost)
UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
Events : 18
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
4 8 49 2 active sync /dev/sdd1
3 8 65 - spare /dev/sde1
5.格式化。
[root@localhost ~]# mkfs.xfs /dev/md5
meta-data=/dev/md5 isize=512 agcount=16, agsize=654720 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=10475520, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
6.挂载使用。
[root@localhost ~]# mkdir /mnt/md5
[root@localhost ~]# mount /dev/md5 /mnt/md5/
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 17G 1014M 16G 6% /
devtmpfs devtmpfs 901M 0 901M 0% /dev
tmpfs tmpfs 912M 0 912M 0% /dev/shm
tmpfs tmpfs 912M 8.7M 904M 1% /run
tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 143M 872M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
/dev/md5 xfs 40G 33M 40G 1% /mnt/md5
7.创建测试文件。
[root@localhost ~]# touch /mnt/md5/test{1..9}.txt
[root@localhost ~]# ls /mnt/md5/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
8.故障模拟。
[root@localhost ~]# mdadm -f /dev/md5 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md5
9.查看测试文件。
[root@localhost ~]# ls /mnt/md5/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
10.查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdd1[4] sde1[3] sdc1[1] sdb1[0](F)
41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [_UU]
[====>................] recovery = 21.0% (4411136/20953088) finish=1.3min speed=210054K/sec
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Aug 25 16:13:44 2019
Raid Level : raid5
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:21:31 2019
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Rebuild Status : 12% complete
Name : localhost:5 (local to host localhost)
UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
Events : 23
Number Major Minor RaidDevice State
3 8 65 0 spare rebuilding /dev/sde1
1 8 33 1 active sync /dev/sdc1
4 8 49 2 active sync /dev/sdd1
0 8 17 - faulty /dev/sdb1
11.再次查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md5 : active raid5 sdd1[4] sde1[3] sdc1[1] sdb1[0](F)
41906176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Aug 25 16:13:44 2019
Raid Level : raid5
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:23:09 2019
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:5 (local to host localhost)
UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
Events : 39
Number Major Minor RaidDevice State
3 8 65 0 active sync /dev/sde1
1 8 33 1 active sync /dev/sdc1
4 8 49 2 active sync /dev/sdd1
0 8 17 - faulty /dev/sdb1
12.移除损坏的磁盘。
[root@localhost ~]# mdadm -r /dev/md5 /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md5
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Aug 25 16:13:44 2019
Raid Level : raid5
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:25:01 2019
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:5 (local to host localhost)
UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
Events : 40
Number Major Minor RaidDevice State
3 8 65 0 active sync /dev/sde1
1 8 33 1 active sync /dev/sdc1
4 8 49 2 active sync /dev/sdd1
13.重新添加热备份盘。
[root@localhost ~]# mdadm -a /dev/md5 /dev/sdb1
mdadm: added /dev/sdb1
[root@localhost ~]# mdadm -D /dev/md5
/dev/md5:
Version : 1.2
Creation Time : Sun Aug 25 16:13:44 2019
Raid Level : raid5
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 3
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:25:22 2019
State : clean
Active Devices : 3
Working Devices : 4
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:5 (local to host localhost)
UUID : a055094e:9adaff79:2edae9b9:0dcc3f1b
Events : 41
Number Major Minor RaidDevice State
3 8 65 0 active sync /dev/sde1
1 8 33 1 active sync /dev/sdc1
4 8 49 2 active sync /dev/sdd1
5 8 17 - spare /dev/sdb1
RAID6
RAID6是在RAID5的基础上改良而成的，RAID6再将数据校验位增加一位，所以允许损坏的硬盘数量也由 RAID5的一个增加到二个。由于同一阵列中两个硬盘同时损坏的概率非常少，所以，RAID6用增加一块硬盘的代价，换来了比RAID5更高的数据安全性。
实验：RAID6创建，格式化，挂载使用，故障模拟，重新添加热备份。
1.添加6块20G的硬盘，分区，类型ID为fd。
[root@localhost ~]# fdisk -l | grep raid
/dev/sdb1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdc1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdd1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sde1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdf1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdg1 2048 41943039 20970496 fd Linux raid autodetect
2.创建RAID6，并添加2个热备份盘。
[root@localhost ~]# mdadm -C -v /dev/md6 -l6 -n4 /dev/sd[b-e]1 -x2 /dev/sd[f-g]1
mdadm: layout defaults to left-symmetric
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 512K
mdadm: size set to 20953088K
mdadm: Fail create md6 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md6 started.
3.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md6 : active raid6 sdg1[5](S) sdf1[4](S) sde1[3] sdd1[2] sdc1[1] sdb1[0]
41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
[===>.................] resync = 18.9% (3962940/20953088) finish=1.3min speed=208575K/sec
unused devices: <none>
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md6 : active raid6 sdg1[5](S) sdf1[4](S) sde1[3] sdd1[2] sdc1[1] sdb1[0]
41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
unused devices: <none>
4.查看RAID6的详细信息。
[root@localhost ~]# mdadm -D /dev/md6
/dev/md6:
Version : 1.2
Creation Time : Sun Aug 25 16:34:36 2019
Raid Level : raid6
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 4
Total Devices : 6
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:34:43 2019
State : clean, resyncing
Active Devices : 4
Working Devices : 6
Failed Devices : 0
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Resync Status : 10% complete
Name : localhost:6 (local to host localhost)
UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
Events : 1
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
3 8 65 3 active sync /dev/sde1
4 8 81 - spare /dev/sdf1
5 8 97 - spare /dev/sdg1
5.格式化。
[root@localhost ~]# mkfs.xfs /dev/md6
meta-data=/dev/md6 isize=512 agcount=16, agsize=654720 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=10475520, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=5120, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
6.挂载使用。
[root@localhost ~]# mkdir /mnt/md6
[root@localhost ~]# mount /dev/md6 /mnt/md6/
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 17G 1014M 16G 6% /
devtmpfs devtmpfs 901M 0 901M 0% /dev
tmpfs tmpfs 912M 0 912M 0% /dev/shm
tmpfs tmpfs 912M 8.7M 903M 1% /run
tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 143M 872M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
/dev/md6 xfs 40G 33M 40G 1% /mnt/md6
7.创建测试文件。
[root@localhost ~]# touch /mnt/md6/test{1..9}.txt
[root@localhost ~]# ls /mnt/md6/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
8.故障模拟。
[root@localhost ~]# mdadm -f /dev/md6 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md6
[root@localhost ~]# mdadm -f /dev/md6 /dev/sdc1
mdadm: set /dev/sdc1 faulty in /dev/md6
9.查看测试文件。
[root@localhost ~]# ls /mnt/md6/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
10.查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md6 : active raid6 sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1](F) sdb1[0](F)
41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/2] [__UU]
[====>................] recovery = 23.8% (4993596/20953088) finish=1.2min speed=208066K/sec
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md6
/dev/md6:
Version : 1.2
Creation Time : Sun Aug 25 16:34:36 2019
Raid Level : raid6
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 4
Total Devices : 6
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:41:09 2019
State : clean, degraded, recovering
Active Devices : 2
Working Devices : 4
Failed Devices : 2
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Rebuild Status : 13% complete
Name : localhost:6 (local to host localhost)
UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
Events : 27
Number Major Minor RaidDevice State
5 8 97 0 spare rebuilding /dev/sdg1
4 8 81 1 spare rebuilding /dev/sdf1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
0 8 17 - faulty /dev/sdb1
1 8 33 - faulty /dev/sdc1
11.再次查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md6 : active raid6 sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1](F) sdb1[0](F)
41906176 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md6
/dev/md6:
Version : 1.2
Creation Time : Sun Aug 25 16:34:36 2019
Raid Level : raid6
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 4
Total Devices : 6
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:42:42 2019
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 2
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:6 (local to host localhost)
UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
Events : 46
Number Major Minor RaidDevice State
5 8 97 0 active sync /dev/sdg1
4 8 81 1 active sync /dev/sdf1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
0 8 17 - faulty /dev/sdb1
1 8 33 - faulty /dev/sdc1
12.移除损坏的磁盘。
[root@localhost ~]# mdadm -r /dev/md6 /dev/sd{b,c}1
mdadm: hot removed /dev/sdb1 from /dev/md6
mdadm: hot removed /dev/sdc1 from /dev/md6
[root@localhost ~]# mdadm -D /dev/md6
/dev/md6:
Version : 1.2
Creation Time : Sun Aug 25 16:34:36 2019
Raid Level : raid6
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:43:43 2019
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:6 (local to host localhost)
UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
Events : 47
Number Major Minor RaidDevice State
5 8 97 0 active sync /dev/sdg1
4 8 81 1 active sync /dev/sdf1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
13.重新添加热备份盘。
[root@localhost ~]# mdadm -a /dev/md6 /dev/sd{b,c}1
mdadm: added /dev/sdb1
mdadm: added /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md6
/dev/md6:
Version : 1.2
Creation Time : Sun Aug 25 16:34:36 2019
Raid Level : raid6
Array Size : 41906176 (39.96 GiB 42.91 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 4
Total Devices : 6
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:44:01 2019
State : clean
Active Devices : 4
Working Devices : 6
Failed Devices : 0
Spare Devices : 2
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : resync
Name : localhost:6 (local to host localhost)
UUID : 7c3d15a2:4066f2c6:742f3e4c:82aae1bb
Events : 49
Number Major Minor RaidDevice State
5 8 97 0 active sync /dev/sdg1
4 8 81 1 active sync /dev/sdf1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1
6 8 17 - spare /dev/sdb1
7 8 33 - spare /dev/sdc1
RAID10
RAID10是先将数据进行镜像操作，然后再对数据进行分组，RAID1在这里就是一个冗余的备份阵列，而RAID0则负责数据的读写阵列。至少要四块盘，两两组合做RAID1，然后做RAID0，RAID10对存储容量的利用率和RAID1一样低，只有50%。Raid10方案造成了50%的磁盘浪费，但是它提供了200%的速度和单磁盘损坏的数据安全性，并且当同时损坏的磁盘不在同一RAID1中，就能保证数据安全性，RAID10能提供比RAID5更好的性能。这种新结构的可扩充性不好，使用此方案比较昂贵。
实验：RAID10创建，格式化，挂载使用，故障模拟，重新添加热备份。
1.添加4块20G的硬盘，分区，类型ID为fd。
[root@localhost ~]# fdisk -l | grep raid
/dev/sdb1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdc1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sdd1 2048 41943039 20970496 fd Linux raid autodetect
/dev/sde1 2048 41943039 20970496 fd Linux raid autodetect
2.创建两个RAID1，不添加热备份盘。
[root@localhost ~]# mdadm -C -v /dev/md101 -l1 -n2 /dev/sd{b,c}1
mdadm: Note: this array has metadata at the start and
may not be suitable as a boot device. If you plan to
store '/boot' on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
--metadata=0.90
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md101 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md101 started.
[root@localhost ~]# mdadm -C -v /dev/md102 -l1 -n2 /dev/sd{d,e}1
mdadm: Note: this array has metadata at the start and
may not be suitable as a boot device. If you plan to
store '/boot' on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
--metadata=0.90
mdadm: size set to 20953088K
Continue creating array? y
mdadm: Fail create md102 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md102 started.
3.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md102 : active raid1 sde1[1] sdd1[0]
20953088 blocks super 1.2 [2/2] [UU]
[=========>...........] resync = 48.4% (10148224/20953088) finish=0.8min speed=200056K/sec
md101 : active raid1 sdc1[1] sdb1[0]
20953088 blocks super 1.2 [2/2] [UU]
[=============>.......] resync = 69.6% (14604672/20953088) finish=0.5min speed=200052K/sec
unused devices: <none>
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md102 : active raid1 sde1[1] sdd1[0]
20953088 blocks super 1.2 [2/2] [UU]
md101 : active raid1 sdc1[1] sdb1[0]
20953088 blocks super 1.2 [2/2] [UU]
unused devices: <none>
4.查看两个RAID1的详细信息。
[root@localhost ~]# mdadm -D /dev/md101
/dev/md101:
Version : 1.2
Creation Time : Sun Aug 25 16:53:00 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:53:58 2019
State : clean, resyncing
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Resync Status : 62% complete
Name : localhost:101 (local to host localhost)
UUID : 80bb4fc5:1a628936:275ba828:17f23330
Events : 9
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md102
/dev/md102:
Version : 1.2
Creation Time : Sun Aug 25 16:53:23 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:54:02 2019
State : clean, resyncing
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Resync Status : 42% complete
Name : localhost:102 (local to host localhost)
UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
Events : 6
Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
1 8 65 1 active sync /dev/sde1
5.创建RAID10。
[root@localhost ~]# mdadm -C -v /dev/md10 -l0 -n2 /dev/md10{1,2}
mdadm: chunk size defaults to 512K
mdadm: Fail create md10 when using /sys/module/md_mod/parameters/new_array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md10 started.
6.查看raidstat状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md102[1] md101[0]
41871360 blocks super 1.2 512k chunks
md102 : active raid1 sde1[1] sdd1[0]
20953088 blocks super 1.2 [2/2] [UU]
md101 : active raid1 sdc1[1] sdb1[0]
20953088 blocks super 1.2 [2/2] [UU]
unused devices: <none>
7.查看RAID10的详细信息。
[root@localhost ~]# mdadm -D /dev/md10
/dev/md10:
Version : 1.2
Creation Time : Sun Aug 25 16:56:08 2019
Raid Level : raid0
Array Size : 41871360 (39.93 GiB 42.88 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:56:08 2019
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Consistency Policy : none
Name : localhost:10 (local to host localhost)
UUID : 23c6abac:b131a049:db25cac8:686fb045
Events : 0
Number Major Minor RaidDevice State
0 9 101 0 active sync /dev/md101
1 9 102 1 active sync /dev/md102
8.格式化。
[root@localhost ~]# mkfs.xfs /dev/md10
meta-data=/dev/md10 isize=512 agcount=16, agsize=654208 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=10467328, imaxpct=25
= sunit=128 swidth=256 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=5112, version=2
= sectsz=512 sunit=8 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
9.挂载使用。
[root@localhost ~]# mkdir /mnt/md10
[root@localhost ~]# mount /dev/md10 /mnt/md10/
[root@localhost ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 17G 1014M 16G 6% /
devtmpfs devtmpfs 901M 0 901M 0% /dev
tmpfs tmpfs 912M 0 912M 0% /dev/shm
tmpfs tmpfs 912M 8.7M 903M 1% /run
tmpfs tmpfs 912M 0 912M 0% /sys/fs/cgroup
/dev/sda1 xfs 1014M 143M 872M 15% /boot
tmpfs tmpfs 183M 0 183M 0% /run/user/0
/dev/md10 xfs 40G 33M 40G 1% /mnt/md10
10.创建测试文件。
[root@localhost ~]# touch /mnt/md10/test{1..9}.txt
[root@localhost ~]# ls /mnt/md10/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
11.故障模拟。
[root@localhost ~]# mdadm -f /dev/md101 /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md101
[root@localhost ~]# mdadm -f /dev/md102 /dev/sdd1
mdadm: set /dev/sdd1 faulty in /dev/md102
12.查看测试文件。
[root@localhost ~]# ls /mnt/md10/
test1.txt test2.txt test3.txt test4.txt test5.txt test6.txt test7.txt test8.txt test9.txt
13.查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md102[1] md101[0]
41871360 blocks super 1.2 512k chunks
md102 : active raid1 sde1[1] sdd1[0](F)
20953088 blocks super 1.2 [2/1] [_U]
md101 : active raid1 sdc1[1] sdb1[0](F)
20953088 blocks super 1.2 [2/1] [_U]
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md101
/dev/md101:
Version : 1.2
Creation Time : Sun Aug 25 16:53:00 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:01:11 2019
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Consistency Policy : resync
Name : localhost:101 (local to host localhost)
UUID : 80bb4fc5:1a628936:275ba828:17f23330
Events : 23
Number Major Minor RaidDevice State
- 0 0 0 removed
1 8 33 1 active sync /dev/sdc1
0 8 17 - faulty /dev/sdb1
[root@localhost ~]# mdadm -D /dev/md102
/dev/md102:
Version : 1.2
Creation Time : Sun Aug 25 16:53:23 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:00:43 2019
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 1
Spare Devices : 0
Consistency Policy : resync
Name : localhost:102 (local to host localhost)
UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
Events : 19
Number Major Minor RaidDevice State
- 0 0 0 removed
1 8 65 1 active sync /dev/sde1
0 8 49 - faulty /dev/sdd1
[root@localhost ~]# mdadm -D /dev/md10
/dev/md10:
Version : 1.2
Creation Time : Sun Aug 25 16:56:08 2019
Raid Level : raid0
Array Size : 41871360 (39.93 GiB 42.88 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 16:56:08 2019
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Consistency Policy : none
Name : localhost:10 (local to host localhost)
UUID : 23c6abac:b131a049:db25cac8:686fb045
Events : 0
Number Major Minor RaidDevice State
0 9 101 0 active sync /dev/md101
1 9 102 1 active sync /dev/md102
14.移除损坏的磁盘。
[root@localhost ~]# mdadm -r /dev/md101 /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md101
[root@localhost ~]# mdadm -r /dev/md102 /dev/sdd1
mdadm: hot removed /dev/sdd1 from /dev/md102
[root@localhost ~]# mdadm -D /dev/md101
/dev/md101:
Version : 1.2
Creation Time : Sun Aug 25 16:53:00 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:04:59 2019
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Name : localhost:101 (local to host localhost)
UUID : 80bb4fc5:1a628936:275ba828:17f23330
Events : 26
Number Major Minor RaidDevice State
- 0 0 0 removed
1 8 33 1 active sync /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md102
/dev/md102:
Version : 1.2
Creation Time : Sun Aug 25 16:53:23 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:05:07 2019
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Name : localhost:102 (local to host localhost)
UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
Events : 20
Number Major Minor RaidDevice State
- 0 0 0 removed
1 8 65 1 active sync /dev/sde1
15.重新添加热备份盘。
[root@localhost ~]# mdadm -a /dev/md101 /dev/sdb1
mdadm: added /dev/sdb1
[root@localhost ~]# mdadm -a /dev/md102 /dev/sdd1
mdadm: added /dev/sdd1
16.再次查看状态。
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md102[1] md101[0]
41871360 blocks super 1.2 512k chunks
md102 : active raid1 sdd1[2] sde1[1]
20953088 blocks super 1.2 [2/1] [_U]
[====>................] recovery = 23.8% (5000704/20953088) finish=1.2min speed=208362K/sec
md101 : active raid1 sdb1[2] sdc1[1]
20953088 blocks super 1.2 [2/1] [_U]
[======>..............] recovery = 32.0% (6712448/20953088) finish=1.1min speed=203407K/sec
unused devices: <none>
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1] [raid0]
md10 : active raid0 md102[1] md101[0]
41871360 blocks super 1.2 512k chunks
md102 : active raid1 sdd1[2] sde1[1]
20953088 blocks super 1.2 [2/2] [UU]
md101 : active raid1 sdb1[2] sdc1[1]
20953088 blocks super 1.2 [2/2] [UU]
unused devices: <none>
[root@localhost ~]# mdadm -D /dev/md101
/dev/md101:
Version : 1.2
Creation Time : Sun Aug 25 16:53:00 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:07:28 2019
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Name : localhost:101 (local to host localhost)
UUID : 80bb4fc5:1a628936:275ba828:17f23330
Events : 45
Number Major Minor RaidDevice State
2 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
[root@localhost ~]# mdadm -D /dev/md102
/dev/md102:
Version : 1.2
Creation Time : Sun Aug 25 16:53:23 2019
Raid Level : raid1
Array Size : 20953088 (19.98 GiB 21.46 GB)
Used Dev Size : 20953088 (19.98 GiB 21.46 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Aug 25 17:07:36 2019
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : resync
Name : localhost:102 (local to host localhost)
UUID : 38abac72:74fa8a53:3a21b5e4:01ae64cd
Events : 39
Number Major Minor RaidDevice State
2 8 49 0 active sync /dev/sdd1
1 8 65 1 active sync /dev/sde1
常用 RAID 间比较
| 名称 | 硬盘数量 | 容量/利用率 | 读性能 | 写性能 | 数据冗余 |
|---|---|---|---|---|---|
| RAID0 | N | N块总和 | N倍 | N倍 | 无，一个故障，丢失所有数据 |
| RAID1 | N（偶数） | 50% | ↑ | ↓ | 写两个设备，允许一个故障 |
| RAID5 | N≥3 | (N-1)/N | ↑↑ | ↓ | 计算校验，允许一个故障 |
| RAID6 | N≥4 | (N-2)/N | ↑↑ | ↓↓ | 双重校验，允许两个故障 |
| RAID10 | N（偶数，N≥4） | 50% | (N/2)倍 | (N/2)倍 | 允许基组中的磁盘各损坏一个 |
一些话
此篇涉及到的操作很简单，但是，有很多的查看占用了大量的篇幅，看关键点，过程都是一个套路，都是重复的。