Capacity expansion and reduction of RBD block storage device (VI)

RBD Expansion and reduction of block storage devices

RBD Blocks are stored in use , You will definitely encounter insufficient disk space , Need to expand , You will also encounter too much disk space , At this time, it is necessary to shrink the volume .

1.RBD Expansion of block storage devices

At present RBD The space of the block storage device is 10GB, Now expand it to 20GB.

1.1. Yes RBD Expand the capacity of the underlying block storage device

from 10GB Expand to 20GB.

[[email protected] ~]# rbd resize -p ceph-rbd-data --image rbd-data.img --size 20G
Resizing image: 100% complete...done.

Check whether the block device is successfully expanded .

[[email protected] ~]# rbd -p ceph-rbd-data --image rbd-data.img info
rbd image 'rbd-data.img':
	size 20 GiB in 5120 objects
	order 22 (4 MiB objects)
	snapshot_count: 0
	id: 1275a517470
	block_name_prefix: rbd_data.1275a517470
	format: 2
	features: layering
	op_features: 
	flags: 
	create_timestamp: Fri Apr  1 17:23:38 2022
	access_timestamp: Fri Apr  1 17:23:38 2022
	modify_timestamp: Fri Apr  1 17:23:38 2022

Block of equipment has been successfully expanded to 20GB, also Object The number of object files has also increased .

1.2. Expand the disk device mapped by the block storage device

RBD Block storage has been successfully expanded , But the mapped disk space is still 10G, Next, we need to expand the disk space .

1. If it is xfs For file systems of type, execute the following command to expand 
[[email protected] ~]# xfs_growfs /dev/rbd0

2. If it is ext4 For file systems of type, execute the following command to expand 
[[email protected] ~]# resize2fs /dev/rbd0

At this time, the disk space has been expanded to 20G.

2.RBD Shrink volume operation of block storage device

At present RBD The space of the block storage device is 20GB, Let's shrink it to 10GB.

2.1. Yes RBD The underlying block storage device is resized

The command is basically the same as the expansion , Just one more --allow-shrink Parameters , It means volume reduction ,--size The parameter indicates the size of the shrinkage .

The process of volume reduction is relatively slow , And may cause data loss , Generally, volume reduction is not recommended .

[[email protected] ~]# rbd resize -p ceph-rbd-data --image rbd-data.img --allow-shrink --size 10G
Resizing image: 100% complete...done.

The capacity of the block storage device is shrunk successfully , It has been reduced to 10G Capacity ,Object The number of object files has also been reduced .

[[email protected] ~]# rbd -p ceph-rbd-data --image rbd-data.img info
rbd image 'rbd-data.img':
	size 10 GiB in 2560 objects			
	order 22 (4 MiB objects)
	snapshot_count: 0
	id: 1275a517470
	block_name_prefix: rbd_data.1275a517470
	format: 2
	features: layering
	op_features: 
	flags: 
	create_timestamp: Fri Apr  1 17:23:38 2022
	access_timestamp: Fri Apr  1 17:23:38 2022
	modify_timestamp: Fri Apr  1 17:23:38 2022

2.2. Refresh the capacity of the disk after the block storage is shrunk

1. Refresh disk capacity 
[[email protected] ~]# umount /dev/rbd0
[[email protected] ~]# resize2fs /dev/rbd0mount

2. Check whether the capacity is reduced 
[[email protected] ~]# df -hT /prod
 file system         type    Capacity    Already used    You can use   Already used %  Mount point 
/dev/rbd0      ext4  9.8G   37M  9.2G    1% /prod

If you are refreshing the disk capacity , The following error is required , Then format the disk , Shrinking operation is not recommended .