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I need to make another parition (/dev/vda2) on an existing disk (/dev/vda, 20G).

umount /mnt/
resize2fs /dev/vda1 10G
df -h

...
/dev/vda1       9.8G  7.8G  1.5G  85% /mnt

So it's ok on this side, but not for fdisk:

 fdisk -l /dev/vda
Disk /dev/vda: 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: gpt
Disk identifier: XXX

Device     Start      End  Sectors Size Type
/dev/vda1   4096 41943006 41938911  20G Linux filesystem
/dev/vda15  2048     4095     2048   1M BIOS boot

/dev/vda1 is still seen as 20G.

However, tune2fs is correct:

 tune2fs -l /dev/vda1
tune2fs 1.43.4 (31-Jan-2017)
Filesystem volume name:   DOROOT
Last mounted on:          /mnt
Filesystem UUID:          XXX
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              652800
Block count:              2621440
Reserved block count:     129948
Free blocks:              510232
Free inodes:              438179
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      1023
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8160
Inode blocks per group:   510
Flex block group size:    16
Filesystem created:       Fri Oct 21 16:17:46 2016
Last mount time:          Thu Nov 23 17:35:09 2017
Last write time:          Thu Nov 23 17:42:31 2017
Mount count:              1
Maximum mount count:      -1
Last checked:             Thu Nov 23 17:31:54 2017
Check interval:           0 (<none>)
Lifetime writes:          456 GB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
Default directory hash:   half_md4
Directory Hash Seed:      XXX
Journal backup:           inode blocks

block count * block size is 10G so what happens to fdisk? How could I partition the remaining 10G?

  • Both tools are right. A "filesystem" doesn't necessarily span over an entire "partition". – don_crissti Nov 23 '17 at 19:12
  • @don_crissti, how would I reduce the partition then? lvreduce? – user8036224 Nov 23 '17 at 19:18
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You have to delete the partition and create a new one.

Show partition information:

Command (m for help): p
Disk /dev/vda: 407.6 GiB, 437629485056 bytes, 854745088 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x5c873cba 
Partition 2 does not start on physical sector boundary. 

Device        Boot        Start     End         Blocks      Id    System 
/dev/vda1      *          2048      1026047     512000      83    Linux
/dev/vda2                 1026048   1640447     307200      8e    Linux LVM

delete the partition:

Command (m for help): d
Partition number (1,2, default 2): 2 

Partition 2 has been deleted.

create a new partition:

Command (m for help): n 

Partition type: 
  p  primary (1 primary, 0 extended, 3 free) 
  e  extended 
Select (default p): *Enter* 

Using default response p. 
Partition number (2-4, default 2): *Enter*
First sector (1026048-854745087, default 1026048): *Enter* 
Last sector, +sectors or +size{K,M,G,T,P} (1026048-854745087, default 854745087): +500M 

Created a new partition 2 of type 'Linux' and of size 500 MiB.

Show partition information:

Command (m for help): p 
Disk /dev/vda: 407.6 GiB, 437629485056 bytes, 854745088 sectors 
Units: sectors of 1 * 512 = 512 bytes 
Sector size (logical/physical): 512 bytes / 4096 bytes 
I/O size (minimum/optimal): 4096 bytes / 4096 bytes 
Disklabel type: dos 
Disk identifier: 0xf6e2b6cb 

Device        Boot        Start     End         Blocks      Id    System 
/dev/vda1      *          2048      1026047     512000      83    Linux 
/dev/vda2                 1026048   2050047     512000      8e    Linux LVM

Write the changes with the w option when you are sure they are correct.

Check the filesystem:

e2fsck /dev/vdb1
e2fsck 1.41.12 (17-May-2010)
Pass 1:Checking inodes, blocks, and sizes
Pass 2:Checking directory structure
Pass 3:Checking directory connectivity
Pass 4:Checking reference counts
Pass 5:Checking group summary information
ext4-1:11/131072 files (0.0% non-contiguous),27050/524128 blocks
  • Thanks for the extensive reply but I don't have a vda2 partition, that's what I want. I only have the main partition (20G with a 10G FS) and the boot (vda15). – user8036224 Nov 23 '17 at 19:32
  • @user8036224 You made the file system smaller. Yes, delete /dev/vda1 and create it new. Its only the partition layout the data will stay there. The new partition can be smaller and create one extra /dev/vda2 – donnie Nov 23 '17 at 19:33
  • I was very suspicious but after reading the original article (access.redhat.com/articles/1190213) you're right. Once should never forget the warning: Warning: If you are recreating a partition in order to allow for more room on a mounted file system, ensure you create it with the same starting disk sector as before. Otherwise the resize operation will not work and the entire file system may be lost. – user8036224 Nov 23 '17 at 20:49

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