Linux 软 RAID 配置
最近出了个 PCIe 3.1 x16 转 4 个 X4 M.2 SSD NVME 固态硬盘转接卡，正好一般的主板上只有一个 m.2 接口，难以扩展容量，将整了个转接卡，上面配上 4 个 nvme 的固态盘。
安装好了，在系统内识别成四块独立的 nvme 盘，不便于管理，就想着用软 RAID 实现加速和扩展。单盘理论速度是 3500MB/s，希望 RAID0 之后会有提升。
在 Linux 中通常是使用 md 模块来实现软件 RAID，这个模块系统在 Linux 3.6 之后集成，但是需要手动安装它的管理工具。
- 安装 mdadm 工具
- 建立分区表（默认msdos）
- 指定磁盘分区类型
- 创建软 raid 盘
- 格式化磁盘
$ sudo apt install mdadm
$ fdisk /dev/nvme0n1
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x7bfec905.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
# 添加新分区
Command (m for help): n
Command action
e extended
p primary partition (1-4)
# 选择分区类型
p
# 设置分区号
Partition number (1-4): 1
First cylinder (1-5221, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-5221, default 5221):
Using default value 5221
# 打印支持的分区格式类型
Command (m for help): l
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
# 更改分区类型
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd # 设置分区类型为RAID
Changed system type of partition 1 to fd (Linux raid autodetect)
Command (m for help): p # 打印信息
Disk /dev/sdb: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x7bfec905
Device Boot Start End Blocks Id System
/dev/sdb1 1 5221 41937651 fd Linux raid autodetect
Command (m for help): w # 保存分区信息
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
至此，准备工作完成了。
创建软 RAID
创建
# 创建一个包含四 nvme 盘的 raid0 盘
$ mdadm --create /dev/md0 --auto yes --level 0 -n4 /dev/nvme{0,1,2,3}n1p1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
| 参数 | 说明 |
|---|---|
| -C/–create | 新建阵列 |
| -a/–auto | 允许mdadm创建设备文件，一般常用参数-a yes一次性创建 |
| -l/–levle | RAID模式，支持RAID0/1/4/5/6/10等 |
| -n/–raid-devices= | 创建阵列中活动磁盘的数量 |
| /dev/md0 | 阵列的设备名称 |
| /dev/nvme{0,1,2,3}n1p1 | 创建阵列中的物理磁盘分区信息 |
查看 RAID 信息
$ cat /proc/mdstat
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5] [raid4] [raid10]
md127 : active raid0 nvme1n1p1[0] nvme3n1p1[3] nvme4n1p1[2] nvme2n1p1[1]
3906516992 blocks super 1.2 512k chunks
$ mdadm -D /dev/md127
/dev/md127:
Version : 1.2
Creation Time : Mon Jun 8 15:03:03 2020
Raid Level : raid0
Array Size : 3906516992 (3725.54 GiB 4000.27 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Mon Jun 8 15:03:03 2020
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Chunk Size : 512K
Consistency Policy : none
Name : ff-206:0 (local to host ff-206)
UUID : 3d6648e7:26309fe3:3d56a600:c7fcc279
Events : 0
Number Major Minor RaidDevice State
0 259 6 0 active sync /dev/nvme1n1p1
1 259 4 1 active sync /dev/nvme2n1p1
2 259 9 2 active sync /dev/nvme4n1p1
3 259 7 3 active sync /dev/nvme3n1p1
写入配置文件
$ echo DEVICE /dev/sd{b,c,d}1 >> /etc/mdadm.conf
$ mdadm -Evs >> /etc/mdadm.conf
$ cat /etc/mdadm.conf
DEVICE /dev/sdb1 /dev/sdc1 /dev/sdd1
ARRAY /dev/md/0 level=raid0 metadata=1.2 num-devices=3 UUID=2c8da2fd:7729efbd:5e414dd0:9cfb9f5f name=Wine:0
devices=/dev/sdb1,/dev/sdc1,/dev/sdd1
格式化分区以及挂载
$ mkfs.ext4 /dev/md0
$ mount /dev/md0 /your/path
把挂载信息写入 fstab （可选）
$ echo '/dev/md0 /SoftRAID ext4 defaults 0 0' >> /etc/fstab
删除软 RAID
- 卸载挂载点
- 停止软件RAID设备
- 删除RAID中的磁盘
- 删除mdadm配置文件
- 删除/etc/fstab中的挂载信息
$ umount /dev/md0
$ mdadm -S /dev/md0
$ mdadm --misc --zero-superblock /dev/nvme{0,1,2,3}n1p1
$ rm -f /etc/mdadm.conf
$ vi /etc/fstab