lvmvdo

Create an VDOPoolLV that will holds VDO data togehther with virtual size VDOLV, that user can use. When the virtual size is not specified, then such LV is created with maximum size that always fits into data volume even if there cannot happen any deduplication and compression (i.e. it can hold uncompressible content of /dev/urandom). When the name of VDOPoolLV is not specified, it tales name from sequence of vpool0, vpool1 ...

Note: As the performance of TRIM/Discard operation is slow for large volumes of VDO type, please try to avoid sending discard requests unless necessary as it may take considerable amount of time to finish discard operation.

lvcreate --type vdo -n VDOLV -L DataSize -V LargeVirtualSize VG/VDOPoolLV
lvcreate --vdo -L DataSize VG

Example

# lvcreate --type vdo -n vdo0 -L 10G -V 100G vg/vdopool0
# mkfs.ext4 -E nodiscard /dev/vg/vdo0

Convert an already created/existing LV into a volume that can hold VDO data and metadata (a volume reference by VDOPoolLV). User will be prompted to confirm such conversion as it is IRREVERSIBLY DESTROYING content of such volume, as it's being immediatelly formated by vdoformat(8) as VDO pool data volume. User can specify virtual size of associated VDOLV with this VDOPoolLV. When the virtual size is not specified, it will set to the maximum size that can keep 100% uncompressible data there.

lvconvert --type vdo-pool -n VDOLV -V VirtualSize VG/VDOPoolLV
lvconvert --vdopool VG/VDOPoolLV

Example

# lvconvert --type vdo-pool -n vdo0 -V10G vg/existinglv

VDO allows to set large variety of option. Lots of these setting can be specified by lvm.conf or profile settings. User can prepare number of different profiles and just specify profile file name. Check output of lvmconfig --type full for detailed description of all individual vdo settings.

Example

# cat <<EOF > vdo.profile
allocation {
	vdo_use_compression=1
	vdo_use_deduplication=1
	vdo_use_metadata_hints=1
	vdo_minimum_io_size=4096
	vdo_block_map_cache_size_mb=128
	vdo_block_map_period=16380
	vdo_check_point_frequency=0
	vdo_use_sparse_index=0
	vdo_index_memory_size_mb=256
	vdo_slab_size_mb=2048
	vdo_ack_threads=1
	vdo_bio_threads=1
	vdo_bio_rotation=64
	vdo_cpu_threads=2
	vdo_hash_zone_threads=1
	vdo_logical_threads=1
	vdo_physical_threads=1
	vdo_write_policy="auto"
	vdo_max_discard=1
}
EOF

# lvcreate --vdo -L10G --metadataprofile vdo.profile vg/vdopool0
# lvcreate --vdo -L10G --config 'allocation/vdo_cpu_threads=4' vg/vdopool1

Disable or enable compression and deduplication for VDO pool LV (the volume that maintains all VDO LV(s) associated with it).

lvchange --compression [y|n] --deduplication [y|n] VG/VDOPoolLV

Example

# lvchange --compression n  vg/vdpool0
# lvchange --deduplication y vg/vdpool1

To quickly check how much data of VDOPoolLV are already consumed use lvs(8). Field Data% will report how much data occupies content of virtual data for VDOLV and how much space is already consumed with all the data and metadata blocks in VDOPoolLV. For a detailed description use vdostats(8) command.

Note: vdostats(8) currently understands only /dev/mapper device names.

Example

# lvcreate --type vdo -L10G -V20G -n vdo0 vg/vdopool0
# mkfs.ext4 -E nodiscard /dev/vg/vdo0
# lvs -a vg

  LV               VG Attr       LSize  Pool     Origin Data%
  vdo0             vg vwi-a-v--- 20.00g vdopool0        0.01
  vdopool0         vg dwi-ao---- 10.00g                 30.16
  [vdopool0_vdata] vg Dwi-ao---- 10.00g

# vdostats --all /dev/mapper/vg-vdopool0
/dev/mapper/vg-vdopool0 :
  version                             : 30
  release version                     : 133524
  data blocks used                    : 79
  ...

Adding more space to hold VDO data and metadata can be made via extension of VDODataLV with commands lvresize(8), lvextend(8).

Note: Size of VDOPoolLV cannot be reduced.

lvextend -L+AddingSize VG/VDOPoolLV

Example

# lvextend -L+50G vg/vdopool0
# lvresize -L300G vg/vdopool1

VDO LV can be extended or reduced as standard LV with commands lvresize(8), lvextend(8), lvreduce(8).

Note: Reduction needs to process TRIM for reduced disk area to unmap used data blocks from VDOPoolLV and it may take a long time.

lvextend -L+AddingSize VG/VDOLV
lvreduce -L-ReducingSize VG/VDOLV

Example

# lvextend -L+50G vg/vdo0
# lvreduce -L-50G vg/vdo1
# lvresize -L200G vg/vdo2

VDODataLV can be activated separately as component LV for examination purposes. It activates data LV in read-only mode and cannot be modified. If the VDODataLV is active as component, any upper LV using this volume CANNOT be activated. User has to deactivate VDODataLV first to continue to use VDOPoolLV.

Example

# lvchange -ay vg/vpool0_vdata
# lvchange -an vg/vpool0_vdata

User can convert/stack VDO with existing volumes.

Using Raid type LV for VDO Data LV.

Example

# lvcreate --type raid1 -L 5G -n vpool vg
# lvconvert --type vdo-pool -V 10G vg/vpool

Cache VDO Data LV (accepts also VDOPoolLV.

Example

# lvcreate -L 5G -V 10G -n vdo1 vg/vpool
# lvcreate --type cache-pool -L 1G -n cpool vg
# lvconvert --cache --cachepool vg/cpool vg/vpool
# lvconvert --uncache vg/vpool

Cache VDO LV.

Example

# lvcreate -L 5G -V 10G -n vdo1 vg/vpool
# lvcreate --type cache-pool -L 1G -n cpool vg
# lvconvert --cache --cachepool vg/cpool vg/vdo1
# lvconvert --uncache vg/vdo1