云主机挂载云硬盘的操作姿势
1. 准备一台有公网IP的云主机，并通过Xshell或SecureCRT等终端模拟软件登录
~$ nova list
+--------------------------------------+---------------------------------+--------+------------+-------------+----------------------------------+
| ID | Name | Status | Task State | Power State | Networks |
+--------------------------------------+---------------------------------+--------+------------+-------------+----------------------------------+
| 72aefa0b-f199-4ddb-b721-9e94f233ced8 | vm-demo | ACTIVE | - | Running | cloud-net-check-vpc=192.168.96.2 |
+--------------------------------------+---------------------------------+--------+------------+-------------+----------------------------------+2. 创建100G云硬盘
~$ cinder create --availability_zone yiqiao1 --volume_type ceph_sas --display_name volume-test 100
+---------------------+--------------------------------------+
| Property | Value |
+---------------------+--------------------------------------+
| attachments | [] |
| availability_zone | yiqiao1 |
| bootable | false |
| created_at | 2019-06-15T08:08:09.164567 |
| display_description | None |
| display_name | volume-test |
| id | c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7 |
| metadata | {} |
| size | 100 |
| snapshot_id | None |
| source_volid | None |
| status | creating |
| volume_type | ceph_sas |
+---------------------+--------------------------------------+
# 云硬盘为available状态时代表可挂载
(my_new_env) likailiang@pubbeta1-nova10:~$ nova volume-list
+--------------------------------------+-----------+---------------------------+------+-------------+--------------------------------------+
| ID | Status | Display Name | Size | Volume Type | Attached to |
+--------------------------------------+-----------+---------------------------+------+-------------+--------------------------------------+
| c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7 | available | volume-test | 100 | ceph_sas | |
+--------------------------------------+-----------+---------------------------+------+-------------+--------------------------------------+
3.挂载云硬盘到云主机
3.1 挂载云硬盘之前云主机外围设备的分区状况
root@virtio-scsi-nodiscard-ceph-sas:~# fdisk -l
Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 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
Disklabel type: dos
Disk identifier: 0x68f54af3
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 41943006 41940959 20G 83 Linux
Disk /dev/sdc: 64 MiB, 67108864 bytes, 131072 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
Disklabel type: dos
Disk identifier: 0x00000000
root@virtio-scsi-nodiscard-ceph-sas:~#
3.2 挂载云硬盘到云主机
(my_new_env) myy@pubbeta1-nova10:~$ nova volume-attach 72aefa0b-f199-4ddb-b721-9e94f233ced8 c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7
+----------+--------------------------------------+
| Property | Value |
+----------+--------------------------------------+
| device | /dev/sdb |
| id | c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7 |
| serverId | 72aefa0b-f199-4ddb-b721-9e94f233ced8 |
| volumeId | c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7 |
+----------+--------------------------------------+
3.3 挂载云硬盘之后云主机外围设备的分区状况
root@virtio-scsi-nodiscard-ceph-sas:~# fdisk -l
Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 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
Disklabel type: dos
Disk identifier: 0x68f54af3
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 41943006 41940959 20G 83 Linux
Disk /dev/sdc: 64 MiB, 67108864 bytes, 131072 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
Disklabel type: dos
Disk identifier: 0x00000000
Disk /dev/sdb: 100 GiB, 107374182400 bytes, 209715200 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
挂载前后的fdisk -l命令执行结果对比，发现挂载云硬盘后会出现一块新的硬盘 /dev/sdb，大小为100G。也可以通过nova show 查看系统扩展卷的信息
(my_new_env) likailiang@pubbeta1-nova10:~$ nova show 72aefa0b-f199-4ddb-b721-9e94f233ced8
+----------------------------------------------+-----------------------------------------------------------------------------------------------------------+
| Property | Value |
+----------------------------------------------+-----------------------------------------------------------------------------------------------------------+
| OS-DCF:diskConfig | MANUAL |
| OS-EXT-AZ:availability_zone | yiqiao1.intel_core_vpc1 |
| OS-EXT-SRV-ATTR:host | pubbeta1-nova90.yq.163.org |
| OS-EXT-SRV-ATTR:hypervisor_hostname | pubbeta1-nova90.yq.163.org |
| OS-EXT-SRV-ATTR:instance_name | instance-00a11c37 |
| OS-EXT-STS:power_state | 1 |
| OS-EXT-STS:task_state | - |
| OS-EXT-STS:vm_state | active |
| OS-SRV-USG:launched_at | 2019-05-23T09:23:07.000000 |
| OS-SRV-USG:terminated_at | - |
| accessIPv4 | |
| accessIPv6 | |
| availability_zone | yiqiao1.intel_core_vpc1 |
| business_type | normal |
| ceph_pool | switch02_sas_vms |
| cloud-net-check-vpc network | 192.168.96.2 |
| config_drive | 1 |
| created | 2019-05-23T09:23:00Z |
| flavor | flavor_54 (54) |
| hostId | 51464028f275ea2bf91cafcb89022951644b8336294a890815b8d83d |
| hypervisor_type | qemu |
| id | 72aefa0b-f199-4ddb-b721-9e94f233ced8 |
| image | debian9.1_virtio_scsi_test (75c0df36-a1cd-4b07-a0a5-fec65d3639c2) |
| instance-qos:read_bps | 104857600 |
| instance-qos:read_iops | 1000 |
| instance-qos:write_bps | 104857600 |
| instance-qos:write_iops | 1000 |
| key_name | id_rsa |
| metadata | {"use-vpc": "true"} |
| name | virtio_scsi_nodiscard_ceph_sas |
| os-extended-volumes:volumes_attached | [{"id": "c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7"}] |
| os-netease-extended-volumes:volumes_attached | [{"delete_on_terminate": false, "id": "c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7", "device_name": "/dev/sdb"}] |
| os-server-status | up |
| os_type | linux |
| progress | 0 |
| status | ACTIVE |
| tenant_id | 1951eb911bf444f299e295ef455bafc4 |
| updated | 2019-05-23T12:14:29Z |
| use_ceph | yes |
| user_id | 7f339ebbc2bb4688ac753c483d97b644 |
+----------------------------------------------+-----------------------------------------------------------------------------------------------------------+
其中 "/dev/sdb"代表设备的名字，
| os-extended-volumes:volumes_attached | [{"id": "c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7"}] |
| os-netease-extended-volumes:volumes_attached | [{"delete_on_terminate": false, "id": "c2a0f8dc-a1a4-4912-a0a4-990b3916e5a7", "device_name": "/dev/sdb"}] |
4.磁盘分区
4.1 创建分区
运行 fdisk /dev/sdb，对数据盘进行分区。根据提示，依次输入 n，p，1，两次回车，wq，分区就开始了。出现Created a new partition 1 of type 'Linux' and of size 100 GiB.代表分区成功。
root@virtio-scsi-nodiscard-ceph-sas:~# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.29.2).
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.
Created a new DOS disklabel with disk identifier 0xcf3e7bcc.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-209715199, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-209715199, default 209715199):
Created a new partition 1 of type 'Linux' and of size 100 GiB.
Command (m for help): wq
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
root@virtio-scsi-nodiscard-ceph-sas:~# 4.2 查看新创建的分区
root@virtio-scsi-nodiscard-ceph-sas:~# fdisk -l
Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 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
Disklabel type: dos
Disk identifier: 0x68f54af3
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 41943006 41940959 20G 83 Linux
Disk /dev/sdc: 64 MiB, 67108864 bytes, 131072 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
Disklabel type: dos
Disk identifier: 0x00000000
Disk /dev/sdb: 100 GiB, 107374182400 bytes, 209715200 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
Disklabel type: dos
Disk identifier: 0xcf3e7bcc
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 209715199 209713152 100G 83 Linux
5. 格式化磁盘
格式化所需时间取决于数据盘大小，100G云硬盘格式化时间大概在3s-10s之间。本次格式化选择的文件系统为ext3，也可选用其他文件格式，如 ext4 等。
root@virtio-scsi-nodiscard-ceph-sas:~# mkfs.ext3 /dev/sdb
mke2fs 1.43.4 (31-Jan-2017)
Found a dos partition table in /dev/sdb
Proceed anyway? (y,N) y
Discarding device blocks: done
Creating filesystem with 26214400 4k blocks and 6553600 inodes
Filesystem UUID: eee12366-e32e-4459-b3d0-30bbfed666ae
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 (131072 blocks): done
Writing superblocks and filesystem accounting information: done 运行 echo /dev/sdb /mnt ext3 defaults 0 0 >> /etc/fstab 写入新分区信息。完成后，可以使用 cat /etc/fstab 命令查看。
root@virtio-scsi-nodiscard-ceph-sas:~# echo /dev/sdb /mnt ext3 defaults 0 0 >> /etc/fstab
root@virtio-scsi-nodiscard-ceph-sas:~# cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
#
# / was on /dev/vda1 during installation
UUID=2287f0e8-f6ef-4c59-95fb-b62ea61f777f / ext4 discard,errors=remount-ro 0 1
/dev/sr0 /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/sdb /mnt ext3 defaults 0 0
通过命令mount -a，实现修改/etc/fstab后不重启且生效。然后执行 df -h 查看分区。如果出现数据盘信息，说明挂载成功，可以使用新分区了。
root@virtio-scsi-nodiscard-ceph-sas:~# mount -a
root@virtio-scsi-nodiscard-ceph-sas:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 0 3.9G 0% /dev
tmpfs 798M 84M 715M 11% /run
/dev/sda1 20G 2.1G 17G 11% /
tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
tmpfs 798M 0 798M 0% /run/user/0
/dev/sdb 98G 61M 93G 1% /mnt
自此云主机挂载云硬盘成功。
6. linux使用dd命令快速生成大文件
dd命令可以轻易实现创建指定大小的文件，如
dd if=/dev/zero of=test bs=1M count=1000
会生成一个1000M的test文件，文件内容为全0（因从/dev/zero中读取，/dev/zero为0源）
root@virtio-scsi-nodiscard-ceph-sas:/mnt# ls
lost+found
root@virtio-scsi-nodiscard-ceph-sas:/mnt# dd if=/dev/zero of=test bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB, 1000 MiB) copied, 2.02557 s, 518 MB/s
root@virtio-scsi-nodiscard-ceph-sas:/mnt# ls -ahl
total 1002M
drwxr-xr-x 3 root root 4.0K Jun 15 16:33 .
drwxr-xr-x 22 root root 4.0K May 23 20:14 ..
drwx------ 2 root root 16K Jun 15 16:22 lost+found
-rw-r--r-- 1 root root 1000M Jun 15 16:33 test
但是这样为实际写入硬盘，文件产生速度取决于硬盘读写速度，如果欲产生超大文件，速度很慢。在某种场景下，我们只想让文件系统认为存在一个超大文件在此，但是并不实际写入硬盘则可以
dd if=/dev/zero of=test bs=1M count=0 seek=100000
此时创建的文件在文件系统中的显示大小为100000MB，但是并不实际占用block，因此创建速度与内存速度相当。seek的作用是跳过输出文件中指定大小的部分，这就达到了创建大文件，但是并不实际写入的目的。当然，因为不实际写入硬盘，所以你在容量只有10G的硬盘上创建100G的此类文件都是可以的
参考：挂载云硬盘https://www.backendcloud.cn/2017/06/30/attach-yunyingpan/