Add a new disk to the server¶
When increasing the amount of disk space assigned to an eCloud virtual machine (VM), the simplest method is to add a new disk to the VM via MyUKFast, and then add that disk into the Volume Group and Logical Volume for the / partition.
Warning
Please be aware that this article uses specific examples, such as sdc or /dev/mapper/eCloud-root.
You may have different requirements or configurations in terms of device names and volumes.
Performing this incorrectly may make irreversible changes to your filesystem or cause data loss, so please proceed with care and caution.
Once an extension has been started, it cannot be reverted.
If you’re unsure of anything or need some help, please contact UKFast Support, by raising a ticket in MyUKFast or calling 0800 230 0032.
Identifying new disk¶
From MyUKFast, you will need to first add a new disk to your VM using the eCloud interface for your required VM. This will hot-add a new disk to your server.
To identify the label for this disk, check dmesg for lines about a new device being added:
[root@ssh ~]# dmesg
[13955.155726] scsi 2:0:2:0: Direct-Access VMware Virtual disk 1.0 PQ: 0 ANSI: 2
[13955.157712] sd 2:0:2:0: Attached scsi generic sg3 type 0
[13955.159156] sd 2:0:2:0: [sdc] 10485760 512-byte logical blocks: (5.36 GB/5.00 GiB)
[13955.159210] sd 2:0:2:0: [sdc] Write Protect is off
[13955.159214] sd 2:0:2:0: [sdc] Mode Sense: 61 00 00 00
[13955.159293] sd 2:0:2:0: [sdc] Cache data unavailable
[13955.159296] sd 2:0:2:0: [sdc] Assuming drive cache: write through
[13955.161472] sdc: unknown partition table
[13955.161769] sd 2:0:2:0: [sdc] Attached SCSI disk
In this case, the new disk is labelled sdc.
You should confirm that this is not already configured as a physical volume in LVM:
[root@ssh ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 eCloud lvm2 a-- 9.51g 0
/dev/sdb eCloud lvm2 a-- 10.00g 0
[root@ssh ~]#
Above shows that /dev/sda2 and /dev/sdb are currently configured as physical volumes; but the /dev/sdc device is not listed.
Create a physical volume from the new disk¶
We need to create a new physical volume (PV) for the new device (sdc) so that we can use it in LVM:
[root@ssh ~]# pvcreate /dev/sdc
Physical volume "/dev/sdc" successfully created
[root@ssh ~]#
Then confirm that it shows up in pvs:
[root@ssh ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/sda2 eCloud lvm2 a-- 9.51g 0
/dev/sdb eCloud lvm2 a-- 15.00g 0
/dev/sdc lvm2 --- 5.00g 5.00g
[root@ssh ~]#
Add the new physical volume into the volume group¶
So that we can assign the new disk space to the logical volume, we need to first add the physical volume into the volume group:
[root@ssh ~]# vgextend eCloud /dev/sdc
Volume group "eCloud" successfully extended
[root@ssh ~]#
Then confirm that the volume group (VG) shows the right total size:
[root@ssh ~]# vgs
VG #PV #LV #SN Attr VSize VFree
eCloud 3 2 0 wz--n- 29.50g 5.00g
[root@ssh ~]#
We need to grow the logical volume (LV) over the new free space - for most people this will be the / partition, but if you have more than one partition, take care to ensure you’re resizing the right one:
[root@ssh ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root eCloud -wi-ao---- 18.53g
swap eCloud -wi-ao---- 1000.00m
[root@ssh ~]#
Extend the logical volume over the free space¶
See also
If you want to create a new partition from this disk - to have / and /home on separate partitions, for example - you would need to create a new Logical Volume instead of extending the existing one.
This should only be performed by advanced users when absolutely required.
For most use cases, a large / partition will be all that is needed.
In this instance, we’ll be doing the most common extension of /. Note the path in this command is /dev/mapper/VG-LV from the table above:
[root@ssh ~]# lvresize -l +100%FREE /dev/mapper/eCloud/root
Size of logical volume eCloud/root changed from 18.53 GiB (4743 extents) to 23.53 GiB (6023 extents).
Logical volume root successfully resized.
[root@ssh ~]#
Confirm that this has resized the LV as expected:
root@ssh ~]# lvs
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
root eCloud -wi-ao---- 23.53g
swap eCloud -wi-ao---- 1000.00m
[root@ssh ~]#
Resize the filesystem to make the new space available¶
Now that the disk and LV show the correct sizes, we can go ahead and resize the filesystem. Some servers use the ext filesystem type, and others user xfs - to identify which yours uses, run the following:
[root@ssh ~]# df -T
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/mapper/eCloud-root xfs 19417088 2235516 17181572 12% /
devtmpfs devtmpfs 1929244 0 1929244 0% /dev
tmpfs tmpfs 1939460 0 1939460 0% /dev/shm
tmpfs tmpfs 1939460 8656 1930804 1% /run
tmpfs tmpfs 1939460 0 1939460 0% /sys/fs/cgroup
/dev/sda1 xfs 508588 211732 296856 42% /boot
tmpfs tmpfs 387892 0 387892 0% /run/user/0
[root@ssh ~]#
In this example, the server is using xfs.
Resizing XFS filesystems¶
To resize an xfs filesystem, run the following - noting the format of /dev/mapper/VG-LV on the device name:
[root@ssh ~]# xfs_growfs /dev/mapper/eCloud-root
Then confirm that the disk shows the correct size in df -h.
Resizing EXT filesystems¶
To resize an ext filesystem, run the following - noting the format of /dev/mapper/VG-LV on the device name:
[root@ssh ~]# resize2fs /dev/mapper/eCloud-root
Then confirm that the disk shows the correct size in df -h