静看光阴荏苒
不管不顾不问不说也不念

CentOS7使用mdadm组软RAID1

其实说个实话,软RAID也好,mdadm也罢,基本就是个玩具,实际的生产环境没多少人会去用软RAID的,都是直接上阵列卡。但玩具也有玩具的价值对嘛,我觉得组软RAID的话,组个RAID0就好了,提升下硬盘性能就行了,其他的什么RAID1/5/10没多大意义,真要是出了啥问题,数据不一定恢复的出来的,而且性能也是个问题。不过有个词说的挺好,叫聊胜于无。。

这篇文章主要演示一下,假设你组了一个软RAID1,如果需要在阵列里面扩容该如何做,以及如果阵列中某块硬盘坏掉了,如何恢复数据并替换新盘到阵列中。

安装mdadm:

yum -y install mdadm

给两块新盘创建RAID分区:

fdisk /dev/vdb
fdisk /dev/vdc

流程:

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-20971519, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): 
Using default value 20971519
Partition 1 of type Linux and of size 10 GiB is set

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

查看硬盘状态:

[root@softraid ~]# lsblk
NAME                     MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0                       11:0    1  918M  0 rom  
vda                      252:0    0   10G  0 disk 
├─vda1                   252:1    0  488M  0 part /boot
└─vda2                   252:2    0  9.5G  0 part 
  ├─centos_softraid-root 253:0    0  8.6G  0 lvm  /
  └─centos_softraid-swap 253:1    0  976M  0 lvm  [SWAP]
vdb                      252:16   0   10G  0 disk 
└─vdb1                   252:17   0   10G  0 part 
vdc                      252:32   0   10G  0 disk 
└─vdc1                   252:33   0   10G  0 part

创建RAID1阵列:

mdadm -C /dev/md0 -l raid1 -n 2 /dev/vd[b-c]1

查看阵列状态:

mdadm -D /dev/md0

一个RAID1阵列就创建好了:

/dev/md0:
           Version : 1.2
     Creation Time : Mon Jun 24 21:39:27 2019
        Raid Level : raid1
        Array Size : 10475520 (9.99 GiB 10.73 GB)
     Used Dev Size : 10475520 (9.99 GiB 10.73 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent

       Update Time : Mon Jun 24 21:40:19 2019
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0

Consistency Policy : resync

              Name : softraid:0  (local to host softraid)
              UUID : 1fb8fc7b:7851fcc4:f4818bdb:0c121770
            Events : 17

    Number   Major   Minor   RaidDevice State
       0     252       17        0      active sync   /dev/vdb1
       1     252       33        1      active sync   /dev/vdc1

创建LVM逻辑卷:

pvcreate /dev/md0
vgcreate imlala-vg /dev/md0
lvcreate -l 100%FREE -n imlala-lv imlala-vg

查看LV完整的卷名:

lvdisplay

回显如下:

--- Logical volume ---
LV Path                /dev/imlala-vg/imlala-lv
LV Name                imlala-lv
VG Name                imlala-vg
LV UUID                hDSh7z-pvgG-1CYY-H6BT-DEDj-ZIit-52EpdL
LV Write Access        read/write
LV Creation host, time softraid, 2019-06-23 21:41:34 +0800
LV Status              available
# open                 0
LV Size                <9.99 GiB
Current LE             2557
Segments               1
Allocation             inherit
Read ahead sectors     auto
- currently set to     256
Block device           253:2

制作XFS文件系统并挂载:

mkfs.xfs /dev/imlala-vg/imlala-lv
mkdir -p /imlala-data
mount /dev/imlala-vg/imlala-lv /imlala-data

查看挂载状态:

[root@softraid ~]# df -hT
Filesystem                        Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos_softraid-root  xfs       8.6G  1.2G  7.5G  14% /
devtmpfs                          devtmpfs  3.9G     0  3.9G   0% /dev
tmpfs                             tmpfs     3.9G     0  3.9G   0% /dev/shm
tmpfs                             tmpfs     3.9G   17M  3.9G   1% /run
tmpfs                             tmpfs     3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/vda1                         xfs       485M  181M  304M  38% /boot
tmpfs                             tmpfs     783M     0  783M   0% /run/user/0
/dev/mapper/imlala--vg-imlala--lv xfs        10G   33M   10G   1% /imlala-data

没问题的话,加到fstab:

echo "/dev/imlala-vg/imlala-lv /imlala-data xfs defaults 0 0" >> /etc/fstab

你可以发现上面这些步骤和我们之前创建RAID0阵列时没多大区别,但如果现在我们服务器内又要加硬盘了,怎么给现有的RAID1阵列扩容呢?RAID1阵列扩容和RAID0阵列扩容就大不相同了。

其实我的建议是直接再组一个新的阵列,不要去动现有的阵列了,因为在mdadm中,给RAID1阵列扩容非常麻烦,但有一些特殊情况,不得不在现有阵列上扩容,有没有办法呢?

办法是有的,在mdadm中给RAID1扩容可以使用替换的方法,什么意思?比如你现在可以看到我们是两个10G的盘组的RAID1,这时候我们再添加两块比10G容量大的硬盘就可以实现扩容。

特别需要注意的是,RAID1最好使用偶数盘,比如2/4/6/8这样的盘位,奇数盘组了没什么意义,或者说奇数盘组RAID1你会浪费掉余下的硬盘。这里我们就增加两块20G的硬盘替换掉之前的两块10G盘,达到一个扩容的目的。

这里为验证扩容不会影响到现有数据,我先往挂载目录内写点数据:

sysbench --test=fileio --file-total-size=2G prepare

可以看到我往里面写了2G数据:

[root@softraid imlala-data]# df -hT
Filesystem                        Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos_softraid-root  xfs       8.6G  1.2G  7.4G  14% /
devtmpfs                          devtmpfs  3.9G     0  3.9G   0% /dev
tmpfs                             tmpfs     3.9G     0  3.9G   0% /dev/shm
tmpfs                             tmpfs     3.9G  8.6M  3.9G   1% /run
tmpfs                             tmpfs     3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/mapper/imlala--vg-imlala--lv xfs        10G  2.1G  8.0G  21% /imlala-data
/dev/vda1                         xfs       485M  181M  304M  38% /boot
tmpfs                             tmpfs     783M     0  783M   0% /run/user/0

还是检查一下当前硬盘状态,可以看到2块船新的硬盘躺在那里等我们开操了:

[root@softraid ~]# lsblk
NAME                        MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sr0                          11:0    1  918M  0 rom   
vda                         252:0    0   10G  0 disk  
├─vda1                      252:1    0  488M  0 part  /boot
└─vda2                      252:2    0  9.5G  0 part  
  ├─centos_softraid-root    253:0    0  8.6G  0 lvm   /
  └─centos_softraid-swap    253:1    0  976M  0 lvm   [SWAP]
vdb                         252:16   0   10G  0 disk  
└─vdb1                      252:17   0   10G  0 part  
  └─md0                       9:0    0   10G  0 raid1 
    └─imlala--vg-imlala--lv 253:2    0   10G  0 lvm   /imlala-data
vdc                         252:32   0   10G  0 disk  
└─vdc1                      252:33   0   10G  0 part  
  └─md0                       9:0    0   10G  0 raid1 
    └─imlala--vg-imlala--lv 253:2    0   10G  0 lvm   /imlala-data
vdd                         252:48   0   20G  0 disk  
vde                         252:64   0   20G  0 disk

还是和之前一样先创建RAID分区:

fdisk /dev/vdd
fdisk /dev/vde

流程:

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-20971519, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): 
Using default value 20971519
Partition 1 of type Linux and of size 10 GiB is set

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

分区完成之后,将两块20G的硬盘加到阵列,设备数由2变为4:

mdadm --grow /dev/md0 --raid-devices=4 --add /dev/vdd1 /dev/vde1

查看阵列状态:

mdadm -D /dev/md0

等待Rebuild完成:

/dev/md0:
           Version : 1.2
     Creation Time : Mon Jun 24 21:39:27 2019
        Raid Level : raid1
        Array Size : 10475520 (9.99 GiB 10.73 GB)
     Used Dev Size : 10475520 (9.99 GiB 10.73 GB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent

       Update Time : Mon Jun 24 22:10:33 2019
             State : clean, degraded, recovering 
    Active Devices : 2
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 2

Consistency Policy : resync

    Rebuild Status : 53% complete

              Name : softraid:0  (local to host softraid)
              UUID : 1fb8fc7b:7851fcc4:f4818bdb:0c121770
            Events : 32

    Number   Major   Minor   RaidDevice State
       0     252       17        0      active sync   /dev/vdb1
       1     252       33        1      active sync   /dev/vdc1
       3     252       65        2      spare rebuilding   /dev/vde1
       2     252       49        3      spare rebuilding   /dev/vdd1

一定要等待阵列Rebuild完成之后,再将旧的两块10G盘从阵列中删除,先将要删除的硬盘标记为故障:

mdadm /dev/md0 -f /dev/vdb1
mdadm /dev/md0 -f /dev/vdc1

然后就可以安全的删除了:

mdadm /dev/md0 -r /dev/vdb1
mdadm /dev/md0 -r /dev/vdc1

将阵列中的设备数量还原为2:

mdadm --grow /dev/md0 --raid-devices=2

最后扩容阵列大小:

mdadm --grow /dev/md0 --size=max

如果正常,终端shell会回显一条提示:

mdadm: component size of /dev/md0 has been set to 20961280K

此时查看阵列状态:

mdadm -D /dev/md0

可以看到阵列容量从10G提升到20G了:

/dev/md0:
           Version : 1.2
     Creation Time : Mon Jun 24 21:39:27 2019
        Raid Level : raid1
        Array Size : 20961280 (19.99 GiB 21.46 GB)
     Used Dev Size : 20961280 (19.99 GiB 21.46 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent

       Update Time : Mon Jun 24 22:17:12 2019
             State : clean 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0

Consistency Policy : resync

              Name : softraid:0  (local to host softraid)
              UUID : 1fb8fc7b:7851fcc4:f4818bdb:0c121770
            Events : 61

    Number   Major   Minor   RaidDevice State
       3     252       65        0      active sync   /dev/vde1
       2     252       49        1      active sync   /dev/vdd1

(重要!)现在我们还需要将RAID阵列的更改进行保存:

mdadm --detail --scan --verbose >> /etc/mdadm.conf

接着重启LVM服务:

systemctl restart lvm2-lvmetad

查看PV:

pvdisplay

还是10G没有变化:

--- Physical volume ---
PV Name               /dev/md0
VG Name               imlala-vg
PV Size               9.99 GiB / not usable 2.00 MiB
Allocatable           yes (but full)
PE Size               4.00 MiB
Total PE              2557
Free PE               0
Allocated PE          2557
PV UUID               EYTFPQ-2Nb3-hCWB-QRVh-ByZd-3K5Q-3TnyZZ

所以现在需要扩容PV:

pvresize /dev/md0

再次查看,可以看到是20G了:

--- Physical volume ---
PV Name               /dev/md0
VG Name               imlala-vg
PV Size               <19.99 GiB / not usable 0   
Allocatable           yes 
PE Size               4.00 MiB
Total PE              5117
Free PE               2560
Allocated PE          2557
PV UUID               EYTFPQ-2Nb3-hCWB-QRVh-ByZd-3K5Q-3TnyZZ

最后我们扩容LV逻辑卷即可:

lvresize -rl +100%FREE /dev/imlala-vg/imlala-lv

完成之后,查看挂载状态和之前写入的文件,可以看到一切正常:

RAID1是有容灾机制的,如果阵列中的某一块硬盘坏掉了,你可以使用和上面同样的方法先将坏掉的硬盘标记为故障,然后使用新盘替换掉旧盘即可完成阵列的重建。

赞(0)
未经允许不得转载:荒岛 » CentOS7使用mdadm组软RAID1
分享到: 更多 (0)

评论 抢沙发

  • 昵称 (必填)
  • 邮箱 (必填)
  • 网址

分享创造快乐

广告合作资源投稿