resize2fs or lvextend to extend encrypted root in a (hosted) VM

[lister171254]

I'm running my mailserver (Ubuntu 10.04 LTS 64 bit server edition) on a VPS and got the people hosting this service to extend the disk do 26GB (from 15)

I have boot root and swap partitions with swap and root encrypted

/dev/xvd already shows the extended size


llist@llmail:~$ sudo fdisk -l

Disk /dev/xvda: 26.8 GB, 26843545600 bytes
255 heads, 63 sectors/track, 3263 cylinders, total 52428800 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 identifier: 0x00027e1c

Device Boot Start End Blocks Id System
/dev/xvda1 * 2048 1075199 536576 83 Linux
/dev/xvda2 1075200 31455231 15190016 8e Linux LVM


llist@llmail:~$ sudo parted -l

Model: Linux device-mapper (crypt) (dm)
Disk /dev/mapper/EncrUbunt-swap_crypt: 998MB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number Start End Size File system Flags
1 0.00B 998MB 998MB linux-swap(v1)


Model: Linux device-mapper (crypt) (dm)
Disk /dev/mapper/EncrUbunt-EncrUbuntu_crypt: 14.6GB
Sector size (logical/physical): 512B/512B
Partition Table: loop

Number Start End Size File system Flags
1 0.00B 14.6GB 14.6GB ext4


Error: /dev/mapper/EncrUbunt-swap: unrecognised disk label

Error: /dev/mapper/EncrUbunt-EncrUbuntu: unrecognised disk label

Model: Xen Virtual Block Device (xvd)
Disk /dev/xvda: 26.8GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
1 1049kB 551MB 549MB primary ext4 boot
2 551MB 16.1GB 15.6GB primary lvm


llist@llmail:~$ sudo lvdisplay
--- Logical volume ---
LV Path /dev/EncrUbunt/swap
LV Name swap
VG Name EncrUbunt
LV UUID cU53xe-gBG3-Lgno-1Kfd-pseN-qckN-ZnuBMH
LV Write Access read/write
LV Creation host, time mail, 2014-05-01 22:30:40 +1000
LV Status available
# open 1
LV Size 952.00 MiB
Current LE 238
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0

--- Logical volume ---
LV Path /dev/EncrUbunt/EncrUbuntu
LV Name EncrUbuntu
VG Name EncrUbunt
LV UUID XvqLCU-6LMr-AadR-uWrU-HGe8-zWwK-LZwIED
LV Write Access read/write
LV Creation host, time mail, 2014-05-01 22:31:22 +1000
LV Status available
# open 1
LV Size 13.55 GiB
Current LE 3470
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:1

While there seems to be a fair amount of 'HowTos' for this, most seem outdated (or wrong) and none specifically handle extending encrypted roots without dismount.


Do I need to extend /dev/xvda2 with parted and then use resize2fs or can I just extend with lvextend?

Thanks,

Leo

[lister171254]

The following approach worked for me on a VirtualBox VM running 14.04 LTS server installed for the purpose of trying different approaches.

The VM was created with 9GB for one disk /dev/sda.

I created

"/boot" with 200MB
"swap" (encrypted) with 400MB
"/" (encrypted) with the rest of the space


I then shut down the VM and extended the storage to 12GN


sudo fdisk /dev/sda

Command (m for help): p

Disk /dev/sda: 12.6 GB, 12582912000 bytes
255 heads, 63 sectors/track, 1529 cylinders, total 24576000 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 identifier: 0x000d2510

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 391167 194560 83 Linux
/dev/sda2 393214 1368063 487425 5 Extended
/dev/sda3 1368064 18872319 8752128 83 Linux
/dev/sda5 393216 1368063 487424 83 Linux

This shows that the disk has 12GB available, but uses less

I then deleted partition 3, which is "/"


Command (m for help): d
Partition number (1-5): 3

Command (m for help): p

Disk /dev/sda: 12.6 GB, 12582912000 bytes
255 heads, 63 sectors/track, 1529 cylinders, total 24576000 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 identifier: 0x000d2510

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 391167 194560 83 Linux
/dev/sda2 393214 1368063 487425 5 Extended
/dev/sda5 393216 1368063 487424 83 Linux

I then created a new partition for with the same start sector as the one I deleted and the (extended) default as the last sector


Command (m for help): n
Partition type:
p primary (1 primary, 1 extended, 2 free)
l logical (numbered from 5)
Select (default p): p
Partition number (1-4, default 3):
Using default value 3
First sector (391168-24575999, default 391168): 1368064
Last sector, +sectors or +size{K,M,G} (1368064-24575999, default 24575999):
Using default value 24575999

Command (m for help): p

Disk /dev/sda: 12.6 GB, 12582912000 bytes
255 heads, 63 sectors/track, 1529 cylinders, total 24576000 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 identifier: 0x000d2510

Device Boot Start End Blocks Id System
/dev/sda1 * 2048 391167 194560 83 Linux
/dev/sda2 393214 1368063 487425 5 Extended
/dev/sda3 1368064 24575999 11603968 83 Linux
/dev/sda5 393216 1368063 487424 83 Linux

Confirming that partition 3 was now extended and the other partitions unaffected I wrote the new partition table


Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

After a reboot, I can now use resize2fs to extend


df -h
Filesystem Size Used Avail Use% Mounted on
udev 1.3G 4.0K 1.3G 1% /dev
tmpfs 257M 468K 257M 1% /run
/dev/dm-0 8.1G 1.7G 6.0G 23% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 4.0K 5.0M 1% /run/lock
none 1.3G 0 1.3G 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 180M 80M 87M 48% /boot

sudo resize2fs /dev/dm-0

resize2fs 1.42.9 (4-Feb-2014)
Filesystem at /dev/dm-0 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/dm-0 is now 2900480 blocks long.

df -h
Filesystem Size Used Avail Use% Mounted on
udev 1.3G 4.0K 1.3G 1% /dev
tmpfs 257M 468K 257M 1% /run
/dev/dm-0 11G 1.7G 8.6G 17% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 1.3G 0 1.3G 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/sda1 180M 80M 87M 48% /boot


Credit goes to this guy https://codesilence.wordpress.com/2013/03/14/live-resizing-of-an-ext4-filesytem-on-linux/