CentOS/Redhat：创建软件RAID 1阵列
时间：2020-01-09 10:34:15 来源:igfitidea点击:
最近，我在安装后向Linux服务器添加了另一个73GB SAS磁盘。
我在旧硬盘上有30GB的空分区。
如何将旧的/dev/sda3和新的/dev/sdb1(均为30GB)转换为RAID 1，以提高NFS服务器的速度和可靠性？
RAID设备是由两个或多个实际块设备创建的虚拟设备。
Linux支持RAID1和其他级别。
您需要在两个磁盘上具有相同大小的分区，即在第二个磁盘上创建与第一个磁盘完全相同的分区，并将类型设置为fd(Linux raid autodetect)。
您需要使用以下命令创建RAID 1。
警告！如果不正确执行这些示例，可能会导致计算机崩溃或丢失数据。
这些示例涉及使用fdisk命令处理磁盘分区以及使用mkfs.ext3命令构建(格式化)文件系统。
因此，在键入以下任一命令之前，请确保"您已备份所有数据"。
我们的示例RAID -1设置具有两个分区：
+------------+
| |
| /dev/sda3 | ===============+
| | |
+------------+ |
37GB | =======> RAID-1 /dev/md0
|
+------------+ |
| | |
| /dev/sdb1 | ===============+
| |
+------------+
37GB
步骤1：列出分区
键入以下命令：
# fdisk -l # fdisk -l /dev/sda
输出示例：
Disk /dev/sda: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 3929 31455270 83 Linux /dev/sda3 3930 8779 38957625 83 Linux /dev/sda4 8780 8910 1052257+ 5 Extended /dev/sda5 8780 8910 1052226 82 Linux swap / Solaris
例如，有目的地使用/dev/sda3(大小为37G)。
现在，列出第二个磁盘分区，输入：
# fdisk -l /dev/sdb
输出示例：
Disk /dev/sdb: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System
步骤2：为/dev/sdb创建37G分区
键入以下命令：
# fdisk /dev/sdb
输出示例：
The number of cylinders for this disk is set to 8910. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help):
要添加新分区，请键入n命令，然后键入p命令，如下所示：
Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-8910, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-8910, default 8910): +37G
要打印分区表类型p命令，请输入：
Command (m for help): p Disk /dev/sdb: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 37 297171 83 Linux
最后，将分区类型设置为Software Raid，即键入0xfd \ *(类型t命令后跟fd代码以将分区类型更改为Software RAID)：
Command (m for help): t Selected partition 1 Hex code (type L to list codes): fd Command (m for help): p Disk /dev/sdb: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 37 297171 fd Linux raid autodetect
保存更改并通过键入w命令退出到shell提示符：
Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
步骤3：为/dev/sda创建/更新37G分区
您需要使用fdisk命令删除/dev/sda3(确保备份了所有数据)和/或将其设置为raid，如下所示：
# fdisk /dev/sda
输出示例：
The number of cylinders for this disk is set to 8910. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): p Disk /dev/sda: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 3929 31455270 83 Linux /dev/sda3 3930 8779 38957625 83 Linux /dev/sda4 8780 8910 1052257+ 5 Extended /dev/sda5 8780 8910 1052226 82 Linux swap / Solaris Command (m for help): t Partition number (1-5): 3 Hex code (type L to list codes): fd Changed system type of partition 3 to fd (Linux raid autodetect) Command (m for help): p Disk /dev/sda: 73.2 GB, 73295462400 bytes 255 heads, 63 sectors/track, 8910 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 3929 31455270 83 Linux /dev/sda3 3930 8779 38957625 fd Linux raid autodetect /dev/sda4 8780 8910 1052257+ 5 Extended /dev/sda5 8780 8910 1052226 82 Linux swap / Solaris Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still uses the old table. The new table will be used at the next reboot. Syncing disks.
重新加载分区表更改
使用partprobe命令无需重新启动该框即可重新加载更改：
# partprobe /dev/sda
或者
# echo 1 > /sys/block/sdb/device/rescan
步骤3：创建RAID 1阵列
要使用/dev/sda3和/dev/sdb1创建RAID1，请输入：
# mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb1
要查看RAID构建进度，请输入：
# watch cat /proc/mdstat
输出示例：
RAID 1镜像
构建完成后，在新的软件RAID设备上创建文件系统，输入：
# mkfs.ext3 /dev/md0
mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 4872896 inodes, 9737360 blocks 486868 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=4294967296 298 block groups 32768 blocks per group, 32768 fragments per group 16352 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000, 7962624 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 39 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
将RAID1挂载到/raid1
键入以下命令：
# mkdir /raid1 # mount /dev/md0 /raid1/ # df -H /raid1/
输出示例：
Filesystem Size Used Avail Use% Mounted on /dev/md0 40G 185M 38G 1% /raid1
如何测试RAID 1阵列速度？
只需使用dd命令，如下所示：
# cd /raid1/ # dd if=/dev/zero of=output bs=8k count=256k # rm output
262144+0 records in 262144+0 records out 2147483648 bytes (2.1 GB) copied, 6.01068 seconds, 357 MB/s
更新/etc/fstab
重新引导系统时，请确保已安装RAID1(注意>>附加重定向)：
# echo '/dev/md0 /raid1 ext3 noatime,rw 0 0' >> /etc/fstab
如何获取有关RAID 1的详细信息？
键入以下命令：
# mdadm --query --detail /dev/md0
输出示例：
/dev/md0:
Version : 0.90
Creation Time : Wed May 26 01:58:53 2010
Raid Level : raid1
Array Size : 38949440 (37.15 GiB 39.88 GB)
Used Dev Size : 38949440 (37.15 GiB 39.88 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Wed May 26 02:18:22 2010
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
UUID : b6f207e4:7f73484f:53f64bfd:e70b77d8
Events : 0.2
Number Major Minor RaidDevice State
0 8 3 0 active sync /dev/sda3
1 8 17 1 active sync /dev/sdb1
