今天在学习阿里云的快照功能时，发现公司每个 ECS 实例下磁盘有系统盘和数据盘两种：
关于系统盘和数据盘，阿里云的官方文档描述如下：
按我的理解，系统盘和数据盘同为阿里云的块存储设备，无本质上的差别，唯一的区别在于，系统盘是随着 ECS 实例创建时，自动挂载到实例中，作为 Linux 中必不可少第一块磁盘，而数据盘则用于磁盘空间扩容，会自动装载到 ESC 实例中，但是需要分区、格式化、挂载后才能使用。
我们公司之前的操作人员在购买 ECS 实例时，为每个 ECS 实例额外购买了 200 个 G 的数据盘，但并未投入生产使用，现在每个服务器依然只有 40 个 G 的存储空间。
查看分区类型：
[root@manager-117 ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT vda 253:0 0 40G 0 disk └─vda1 253:1 0 40G 0 part / [root@manager-117 ~]# parted /dev/vda print Model: Virtio Block Device (virtblk) Disk /dev/vda: 42.9GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 42.9GB 42.9GB primary ext4 boot上面分区表类型显示的 msdos ，表示磁盘是 MBR 分区类型，MBR 分区使用 fdisk 命令磁盘分区，GPT分区使用 gdisk 命令磁盘分区；
使用 fdisk 查看是否存在没有分区的磁盘：
[root@manager-117 ~]# fdisk -l Disk /dev/vda: 42.9 GB, 42949672960 bytes, 83886080 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: 0x0008d73a Device Boot Start End Blocks Id System /dev/vda1 * 2048 83884031 41940992 83 Linux Disk /dev/vdb: 214.7 GB, 214748364800 bytes, 419430400 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 [root@manager-117 ~]#上面表示 系统中已经装载了一块新磁盘 /dev/vdb, 大小为214.7个G，但并未进行挂载使用；
将该磁盘添加到系统中：
第一步：分区
[root@manager-117 ~]# fdisk /dev/vdb Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Device does not contain a recognized partition table Building a new DOS disklabel with disk identifier 0xba6dca54. Command (m for help): p Disk /dev/vdb: 214.7 GB, 214748364800 bytes, 419430400 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: 0xba6dca54 Device Boot Start End Blocks Id System 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): First sector (2048-419430399, default 2048): Using default value 2048 Last sector, +sectors or +size{K,M,G} (2048-419430399, default 419430399): Using default value 419430399 Partition 1 of type Linux and of size 200 GiB is set Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.第二步：格式化
[root@manager-117 ~]# mkfs -t ext4 /dev/vdb1 mke2fs 1.42.9 (28-Dec-2013) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 13107200 inodes, 52428544 blocks 2621427 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=2199912448 1600 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000, 7962624, 11239424, 20480000, 23887872 Allocating group tables: done Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done第三步：挂载
[root@manager-117 ~]# mkdir /data [root@manager-117 ~]# mount /dev/vdb1 /data查看是否生效：
[root@manager-117 ~]# df -hT Filesystem Type Size Used Avail Use% Mounted on /dev/vda1 ext4 40G 8.2G 30G 22% / devtmpfs devtmpfs 16G 0 16G 0% /dev tmpfs tmpfs 16G 0 16G 0% /dev/shm tmpfs tmpfs 16G 1.7M 16G 1% /run tmpfs tmpfs 16G 0 16G 0% /sys/fs/cgroup overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/983380badcc0be507c6d06b5be709c97b47cdd85d79c715243f9fc07116417c5/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/516a25698415edc61d19f84efac8e4e1f527e87198be7b162d81bb31fdeae92c/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/5c9c523e0e88b12064e943324b20b5e12e190a5b06ffe24b71560d64a904e9b2/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/5fe03ffe737bf07974debe1b342c2e6686f1bded544dfb708a7f298847daf812/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/ec71117f3c28b8e45a5091660cf3a61cff3f85096b600eaccf1accb937b49835/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/dd94d5644aee5c729fd61a53b1d812660f6781c0a6562575f3a004fad54086c5/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/654f6d7b653ee718bdc401e2a9519d68e05cae05fcb4520d8408b32514256e56/shm shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/668915046ca6d12ffd95cb0a516d1a4a972e86c1909b6d77fee49cd699b7315a/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/2cd78f1ecbd336ecd68dd8601e33dd9ed7aa4ad369547693f4dd375f3b2de95b/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/cc79290fa6045524cc491041072c0425790b65ba5c8f3c5b631796c37523ee9a/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/4d359227711da76c9c18ed42739a1434bc6b27e56ddd9a323f7b560e6a241b4b/shm shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/2b18d76ff658663506bc689396034672d433f2b61df75d3466e3d6ac3f87df7f/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/256beaa7ae061d0372648f063c715cb54d2771fd48b35168344b93190eb1957e/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/46457f18b4da731dd5414784ee03be566b4cd7dc27eba3662a2beaaf2a24002d/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/9af4017943e11e8638b0f3b8739e955852ddb7336637d002b6d360aaacc04254/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/1b26531a4f593f024db0ecaedcd2d82c25a1e439abc8602e9288a0a60eb97dbc/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/77f21520cd189edab98be30b848b8e0056003b462becca8d135f5a7c8a028d58/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/34d7b4d5584d820377e119756682ba06a9d64c06677c0851517b208c4de88355/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/b22de236151c1a95e3cf61811fe523ee9a80f0b28c0a8a665fb68cb250be75cb/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/666be0ccc3422e247b9baaac419bf67593306b182b38eb3a6e6f436a49e9752f/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/4721d2cf6e161b9f3b4459beaa58cb13ba29b52efe96a91b1f7cc30e11dc12ad/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/23b48a996e87fbf128f8dcc20346f90b48b231015230ad25c1bdf963ba79686e/merged overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/88de1d1282dd17dbe9a6cf69b2a42e164e47333784c7b5ece9bad72d22d19dc5/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/2ab3a4af5c4b28194e2b54145c796f78ef04227476d76442904279e00b60cc1c/shm shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/c788033d7726e00610d81ff44a78782e5d96edada766a3621be222384f9f2c17/shm shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/c675e9f1ea8c4740a480d8e7e1bb120c81b4d886feb1b057fe5d696da5ca5c64/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/7530a155bb76f55dddf470cd45c29b5c3b8eb57cae664ddebd3df7b302f8305d/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/69234b2848255d46d834038caa187b3a2144fc8d5a4d4246bb3301ecac2b9869/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/28db3e41db46c8b3060661f2d6c3288915f1eafc23a69bbf64ae2ae0589bdb1f/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/40fafe723800602d4ab6a6ca48645058d943497e8c98aa54446312e6a658875a/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/c443b9cd9e2b8c2fe060b3f28c251e23a4245eba6211ec110a434c05e9b6675c/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/cf71512e3999b11b5cfbf62ac42f4c3343d9074ceb43647acc5b0b65e2bf2607/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/7f98a02f4521a260625ab8fadc512a8d86d511b503ff6aa5f5832ca47fd8854e/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/c41b80cbe8809609410d728c8693250e9e835409f4a90f18afe7988f84b58c4a/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/927876eae87803f3146c26957ef7c250668b3aa279a2e033ab297941acffc4c7/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/dfa3bca2dda6b924e9bd908d0ad1ef73e8500cb7d60f1a17c255092e1d081078/shm overlay overlay 40G 8.2G 30G 22% /var/lib/docker/overlay/f2b5ae6c01cbf29de8268258810cebe33f4ad8daf29ac27c2753b80a4d7171d5/merged shm tmpfs 64M 0 64M 0% /var/lib/docker/containers/1cd214f505a5a3483a0c32f0706694684abc56bc59887326e3f84ec525175515/shm tmpfs tmpfs 3.2G 0 3.2G 0% /run/user/0 /dev/vdb1 ext4 197G 61M 187G 1% /data已将该磁盘挂载到 linux 系统中。
注意：使用 mount 命令挂载的分区在系统重启时会失效，需再次使用 mount 命令进行挂载，也可以编辑 /etc/fstab 文件设置开机自动挂载。
第四步：设置开机自动挂载
获取分区的 uuid：
[root@manager-117 ~]# blkid /dev/vda1: UUID="eb448abb-3012-4d8d-bcde-94434d586a31" TYPE="ext4" /dev/vdb1: UUID="8ec5348c-3c98-4bd4-98eb-66b5c657927e" TYPE="ext4"编辑 /etc/fstab 文件：
# # /etc/fstab # Created by anaconda on Sun Oct 15 15:19:00 2017 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=eb448abb-3012-4d8d-bcde-94434d586a31 / ext4 defaults 1 1 UUID=8ec5348c-3c98-4bd4-98eb-66b5c657927e /data ext4 defaults 1 2
关于 /etc/fstab 参数说明：
第一列是要挂载的分区的标识。
可以是实际分区名，也可以是实际分区的卷标（Lable），或者是 UUID。
第二列是挂载点。
挂载点必须为当前已经存在的目录，最好为空目录。
第三列为此分区的文件系统类型。
此字段须与分区格式化时使用的类型相同，也可以使用 auto 这一特殊的语法，使系统自动侦测目标分区的分区类型。auto通常用于可移动设备的挂载。
第四列是挂载的选项。
用于设置挂载的参数，常见参数如下：
auto 系统自动挂载，fstab默认就是这个选项； defaults rw, suid, dev, exec, auto, nouser, and async； noauto 开机不自动挂载； nouser 只有超级用户可以挂载； ro 按只读权限挂载； rw 按可读可写权限挂载； user 任何用户都可以挂载； 请注意光驱和软驱只有在装有介质时才可以进行挂载，因此它是noauto。
第五列是dump备份设置。
当其值设置为1时，将允许dump备份程序备份；设置为0时，忽略备份操作；
第六列是fsck磁盘检查设置。
其值是一个顺序。当其值为0时，永远不检查；而 / 根目录分区永远都为1。其它分区从2开始，数字越小越先检查，如果两个分区的数字相同，则同时检查。
