Introduction

We all know that using lv logical volumes can be easily expanded.
But when the original disk is not a logical volume and there is data on it, how to expand it?
Because the expansion can only be done if the disk type is the logical volume lvm.
Then, after directly pvcreating the disk with data into the virtual volume lvm, will it damage the data?
Let's test it today.

add hard drive

Add a 5G disk to the virtual machine as an experiment

View the current partition

lsblk

You can see that the newly added 5G disk sdb is ready to use

[root@C8-196 ~]# lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0  200G  0 disk 
├─sda1        8:1    0    1G  0 part /boot
└─sda2        8:2    0  199G  0 part 
  ├─cl-root 253:0    0   70G  0 lvm  /
  ├─cl-swap 253:1    0    2G  0 lvm  [SWAP]
  └─cl-home 253:2    0  127G  0 lvm  /home
sdb           8:16   0    5G  0 disk

Partition using the traditional method

fdisk /dev/sdb

Create a primary partition

[root@C8-196 ~]# fdisk /dev/sdb

Welcome to fdisk (util-linux 2.32.1).
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 0x53b270c9.

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): 
First sector (2048-10485759, default 2048): 
Last sector, +sectors or +size{
    
    K,M,G,T,P} (2048-10485759, default 10485759): 

Created a new partition 1 of type 'Linux' and of size 5 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Check the partition situation again, sdb is divided into a primary partition, the TYPE is part, and the size is 5G

[root@C8-196 ~]# lsblk
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda           8:0    0  200G  0 disk 
├─sda1        8:1    0    1G  0 part /boot
└─sda2        8:2    0  199G  0 part 
  ├─cl-root 253:0    0   70G  0 lvm  /
  ├─cl-swap 253:1    0    2G  0 lvm  [SWAP]
  └─cl-home 253:2    0  127G  0 lvm  /home
sdb           8:16   0    5G  0 disk 
└─sdb1        8:17   0    5G  0 part

Create a filesystem on the newly created partition

format sdb1 using xfs

[root@C8-196 ~]# mkfs.xfs /dev/sdb1
meta-data=/dev/sdb1              isize=512    agcount=4, agsize=327616 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=1310464, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

Create a mount point and mount the new partition

Create a directory data under the root and mount the new partition to this directory

[root@C8-196 ~]# mkdir -v /data&& mount /dev/sdb1 /data&&df -Th
mkdir: created directory '/data'
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  876M     0  876M   0% /dev
tmpfs               tmpfs     896M     0  896M   0% /dev/shm
tmpfs               tmpfs     896M   17M  879M   2% /run
tmpfs               tmpfs     896M     0  896M   0% /sys/fs/cgroup
/dev/mapper/cl-root xfs        70G  2.3G   68G   4% /
/dev/mapper/cl-home xfs       127G  939M  126G   1% /home
/dev/sda1           xfs      1014M  197M  818M  20% /boot
tmpfs               tmpfs     180M     0  180M   0% /run/user/0
/dev/sdb1           xfs       5.0G   68M  5.0G   2% /data

Create a test file on the new disk partition

Write 100 files to disk for data testing
for i in {1..100};do $(time dd if=/dev/zero of=/data/testw$i.db bs=4k count=10000);done&&ll /data&&df -Th

[root@C8-196 ~]# for i in {1..100};do $(time dd if=/dev/zero of=/data/testw$i.db bs=4k count=10000);done&&ll /data&&df -Th
10000+0 records in
10000+0 records out
40960000 bytes (41 MB, 39 MiB) copied, 0.0162844 s, 2.5 GB/s

## 中间的省略……
real	0m0.016s
user	0m0.002s
sys	0m0.014s
10000+0 records in
10000+0 records out
40960000 bytes (41 MB, 39 MiB) copied, 0.0153671 s, 2.7 GB/s

real	0m0.017s
user	0m0.001s
sys	0m0.015s
total 4000000
## 磁盘中已经有写入的文件了
-rw-r--r-- 1 root root 40960000 Mar  2 21:15 testw100.db
-rw-r--r-- 1 root root 40960000 Mar  2 21:15 testw10.db
-rw-r--r-- 1 root root 40960000 Mar  2 21:15 testw11.db
## …… 中间的省略
-rw-r--r-- 1 root root 40960000 Mar  2 21:15 testw99.db
-rw-r--r-- 1 root root 40960000 Mar  2 21:15 testw9.db
## 分区已经占了78%了
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  876M     0  876M   0% /dev
tmpfs               tmpfs     896M     0  896M   0% /dev/shm
tmpfs               tmpfs     896M   17M  879M   2% /run
tmpfs               tmpfs     896M     0  896M   0% /sys/fs/cgroup
/dev/mapper/cl-root xfs        70G  2.3G   68G   4% /
/dev/mapper/cl-home xfs       127G  939M  126G   1% /home
/dev/sda1           xfs      1014M  197M  818M  20% /boot
tmpfs               tmpfs     180M     0  180M   0% /run/user/0
/dev/sdb1           xfs       5.0G  3.9G  1.2G  78% /data

Do pvcreate directly on the partition with data

Obviously, for security reasons, mounted partitions cannot be directly pvcreated

[root@C8-196 ~]# 
[root@C8-196 ~]# type pvcreate 
pvcreate is /usr/sbin/pvcreate
[root@C8-196 ~]# pvcreate /dev/sdb1
  Can't open /dev/sdb1 exclusively.  Mounted filesystem?
  Can't open /dev/sdb1 exclusively.  Mounted filesystem?

pvcreate again after umount

After the umount is dropped, the pvcreate is successful, although it is prompted that there is an xfs file system on the partition

[root@C8-196 ~]# umount /dev/sdb1
[root@C8-196 ~]# pvcreate /dev/sdb1
WARNING: xfs signature detected on /dev/sdb1 at offset 0. Wipe it? [y/n]: y
  Wiping xfs signature on /dev/sdb1.
  Physical volume "/dev/sdb1" successfully created.

But it feels like pvcreate has destroyed the existing file system

Create logical volumes

[root@C8-196 ~]# vgcreate vg_data /dev/sdb1
  Volume group "vg_data" successfully created
[root@C8-196 ~]# lvcreate -l 100%FREE -n data_lv vg_data
  Logical volume "data_lv" created.
[root@C8-196 ~]# pvs&&vgs&&lvs
  PV         VG      Fmt  Attr PSize    PFree
  /dev/sda2  cl      lvm2 a--  <199.00g    0 
  /dev/sdb1  vg_data lvm2 a--    <5.00g    0 
  VG      #PV #LV #SN Attr   VSize    VFree
  cl        1   3   0 wz--n- <199.00g    0 
  vg_data   1   1   0 wz--n-   <5.00g    0 
  LV      VG      Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  home    cl      -wi-ao---- 126.96g                                                    
  root    cl      -wi-ao----  70.00g                                                    
  swap    cl      -wi-ao----   2.03g                                                    
  data_lv vg_data -wi-a-----  <5.00g

Try to mount /dev/sdb1 again

Apparently it can't be loaded

[root@C8-196 ~]# mount /dev/sdb1 /data
mount: /data: unknown filesystem type 'LVM2_member'.

Try to mount the newly created lvm logical volume directly

Obviously, there is no file system that can't be mounted

[root@C8-196 ~]# ll /dev/mapper/vg_data-data_lv 
lrwxrwxrwx 1 root root 7 Mar  2 21:28 /dev/mapper/vg_data-data_lv -> ../dm-3
[root@C8-196 ~]# ll /dev/vg_data/
total 0
lrwxrwxrwx 1 root root 7 Mar  2 21:28 data_lv -> ../dm-3
[root@C8-196 ~]# mount /dev/mapper/vg_data-data_lv /data
mount: /data: wrong fs type, bad option, bad superblock on /dev/mapper/vg_data-data_lv, missing codepage or helper program, or other error.

[root@C8-196 ~]# mount /dev/vg_data/data_lv /data
mount: /data: wrong fs type, bad option, bad superblock on /dev/mapper/vg_data-data_lv, missing codepage or helper program, or other error.

Create a file system on the new logical volume

Use xfs to format the newly created logical volume, format it, you know

[root@C8-196 ~]# mkfs.xfs /dev/mapper/vg_data-data_lv 
meta-data=/dev/mapper/vg_data-data_lv isize=512    agcount=4, agsize=327424 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=1
data     =                       bsize=4096   blocks=1309696, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

Mount the logical volume to the former data directory

mount /dev/mapper/vg_data-data_lv /data

[root@C8-196 ~]# mount /dev/mapper/vg_data-data_lv /data
[root@C8-196 ~]# df -Th
Filesystem                  Type      Size  Used Avail Use% Mounted on
devtmpfs                    devtmpfs  876M     0  876M   0% /dev
tmpfs                       tmpfs     896M     0  896M   0% /dev/shm
tmpfs                       tmpfs     896M   17M  879M   2% /run
tmpfs                       tmpfs     896M     0  896M   0% /sys/fs/cgroup
/dev/mapper/cl-root         xfs        70G  2.3G   68G   4% /
/dev/mapper/cl-home         xfs       127G  939M  126G   1% /home
/dev/sda1                   xfs      1014M  197M  818M  20% /boot
tmpfs                       tmpfs     180M     0  180M   0% /run/user/0
/dev/mapper/vg_data-data_lv xfs       5.0G   68M  5.0G   2% /data

Check if there are files in the directory

It's time to witness the miracle!

/dev/mapper/vg_data-data_lv xfs       5.0G   68M  5.0G   2% /data
[root@C8-196 ~]# ll /data
total 0

Obviously, the wool is gone.
If there is production data in this directory, you can leave!
Another new way to delete the library and run away!

in conclusion

Using pvcreate cannot directly create pv for mounted partitions
Use pvcreate to directly create pv for a partition that has data and has been unmounted, and it will prompt that the file system exists

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Whether the creation of logical volume pvcreate will damage the original data test for non-logical volume expansion under Linux

Introduction

add hard drive

View the current partition

Partition using the traditional method

Create a filesystem on the newly created partition

Create a mount point and mount the new partition

Create a test file on the new disk partition

Do pvcreate directly on the partition with data

pvcreate again after umount

Create logical volumes

Try to mount /dev/sdb1 again

Try to mount the newly created lvm logical volume directly

Create a file system on the new logical volume

Mount the logical volume to the former data directory

Check if there are files in the directory

in conclusion

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Guess you like

Whether the creation of logical volume pvcreate will damage the original data test for non-logical volume expansion under Linux

Introduction

add hard drive

View the current partition

Partition using the traditional method

Create a filesystem on the newly created partition

Create a mount point and mount the new partition

Create a test file on the new disk partition

Do pvcreate directly on the partition with data

pvcreate again after umount

Create logical volumes

Try to mount /dev/sdb1 again

Try to mount the newly created lvm logical volume directly

Create a file system on the new logical volume

Mount the logical volume to the former data directory

Check if there are files in the directory

in conclusion

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be gone ~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be gone ~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be gone ~

Guess you like

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~

Using pvcreate to create pv on a partition with data will destroy the file system, and the file will be _gone~