红帽全球峰会3.10. Changing the deduplication settings on an LVM-VDO volume
By default, the deduplication of a VDO pool logical volume (LV) is enabled. To save memory, you can disable deduplication. Enable or disable deduplication by using the lvchange command.
Because of the way that VDO handles ongoing parallel I/O operations, a VDO volume continues to identify duplicate data within those operations. For example, if a VM clone operation is in progress and a VDO volume has many duplicate blocks in close proximity, then the volume can still achieve some amount of space savings by using deduplication. The index state of the volume does not affect the process.
Prerequisites
- An LVM-VDO volume exists on your system.
Procedure
Check the deduplication status for your logical volumes:
# lvs -o+vdo_deduplication,vdo_index_stateLV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert VDODeduplication VDOIndexState <vdo_name> <vg_name> vwi-a-v--- 1.00t vpool0 0.00 enabled online vpool0 <vg_name> dwi------- <15.00g 20.03 enabled onlineDisable the deduplication for VDOPoolLV:
# lvchange --deduplication n <vg_name>/<vdo_pool_name>If you want to enable the deduplication, use the
yoption instead ofn.
Verification
View the current status of deduplication:
# lvs -o+vdo_deduplication,vdo_index_stateLV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert VDODeduplication VDOIndexState <vdo_name> <vg_name> vwi-a-v--- 1.00t vpool0 0.00 closed vpool0 <vg_name> dwi------- <15.00g 20.03 closed
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