linux trim raid,CentOS7下组建软Raid磁盘阵列并开启Trim|延长SSD寿命

给自己24核24G内存的独服买了个120G的SSD作OS盘，然后两个1.5T的SSD组raid1作数据库盘，加上原有的3个2THDD组raid5作仓库盘。不多说了直接上干货：

先fdisk -l看看磁盘分区情况，可以看到总共有6个盘，分别是sd[a~f]：

Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes, 3907029168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/sda: 120.0 GB, 120034123776 bytes, 234441648 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk label type: dos

Disk identifier: 0x00007ae4

Device Boot Start End Blocks Id System

/dev/sda1 * 2048 2099199 1048576 83 Linux

/dev/sda2 2099200 234440703 116170752 8e Linux LVM

Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes, 3907029168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes, 3907029168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/sde: 1500.3 GB, 1500301910016 bytes, 2930277168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk /dev/sdf: 1500.3 GB, 1500301910016 bytes, 2930277168 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

记下每个盘对应的盘号，留着备用。

然后安装centos下的软raid阵列工具mdadm：

yum -y install mdadm

安装完后即可配置阵列：

[root@hostname ~]# mdadm -C /dev/md0 -ayes -l5 -n3 /dev/sd[b,c,d]

mdadm: Defaulting to version 1.2 metadata

mdadm: array /dev/md0 started.

[root@hostname ~]# mdadm -C /dev/md1 -ayes -l1 -n2 /dev/sd[e,f]

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

Continue creating array? y

mdadm: Defaulting to version 1.2 metadata

mdadm: array /dev/md1 started.

中间如果弹出警告不管他就好，反正是作为数据盘用而不是作为启动盘。

上述步骤操作完之后系统就自动开始奇偶校验了，然后通过以下命令查看进度：

[root@hostname ~]# cat /proc/mdstat

Personalities : [raid6] [raid5] [raid4] [raid1]

md1 : active raid1 sdf[1] sde[0]

1465006464 blocks super 1.2 [2/2] [UU]

[=>...................] resync = 7.5% (110671488/1465006464) finish=229.2min speed=98449K/sec

bitmap: 11/11 pages [44KB], 65536KB chunk

md0 : active raid5 sdd[3] sdc[1] sdb[0]

3906764800 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [UU_]

[>....................] recovery = 3.2% (63790592/1953382400) finish=571.6min speed=55093K/sec

bitmap: 0/15 pages [0KB], 65536KB chunk

等奇偶校验好了之后需要创建配置文件：

echo DEVICE /dev/sd{b,c,d} >> /etc/mdadm.conf

echo DEVICE /dev/sd{e,f} >> /etc/mdadm.conf

mdadm -Evs >> /etc/mdadm.conf

然后格式化、写入挂载信息、挂载

开启trim和定期指定trim：

fstrim --verbose --all

systemctl enable fstrim.timer

另外linux会划出来一部分磁盘空间做swap，会导致大量写入，因此需要做一些限制：

vi /etc/sysctl.conf

#写入系统文件，增加下面两行：

vm.swappiness=1

vm.vfs_cache_pressure=50

#保存并生效：

sysctl -p

#启动tmpfs服务

systemctl enable tmp.mount

另外关于磁盘格式的问题，数据库还是选用xfs吧，具体可以参考其他文章中对磁盘格式的对比

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