ivampiresp/Spdk
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

doc/lvol: add thin-provisioning section

Browse Source 
Signed-off-by: <tomaszx.kulasek@intel.com>
Change-Id: Ib3516b85a721363526deab14170da87a8d9232f1
Reviewed-on: https://review.gerrithub.io/415298
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
This commit is contained in:
Tomasz Kulasek 2018-06-14 11:40:20 +02:00 committed by Jim Harris
parent c8b03c762f
commit ac34a2dfed
3 changed files with 18 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
doc/img/lvol_thin_provisioning.svg Normal file
View File

File diff suppressed because one or more lines are too long
Side by Side

After

Width:  |  Height:  |  Size: 12 KiB

3
doc/img/lvol_thin_provisioning_write.svg Normal file
View File

File diff suppressed because one or more lines are too long
Side by Side

After

Width:  |  Height:  |  Size: 11 KiB

12
doc/lvol.md
View File

@ -28,6 +28,18 @@ A logical volume block device translates generic SPDK block device I/O (spdk_bde
Size of the new bdev will be rounded up to nearest multiple of cluster_size.
By default lvol bdevs claim part of lvol store equal to their set size. When thin provision option is enabled, no space is taken from lvol store until data is written to lvol bdev.
## Thin provisioning {#lvol_thin_provisioning}
Thin provisioned lvols rely on dynamic cluster allocation (e.g. when the first write operation on a cluster is performed), only space required to store data is used and unallocated clusters are obtained from underlying device (e.g. zeroes_dev).
Sample write operations of thin provisioned blob are shown on the diagram below:
![Writing clusters to the thin provisioned blob](lvol_thin_provisioning_write.svg)
Sample read operations and the structure of thin provisioned blob are shown on the diagram below:
![Reading clusters from thin provisioned blob](lvol_thin_provisioning.svg)
## Snapshots and clone {#lvol_snapshots}
Logical volumes support snapshots and clones functionality. User may at any given time create snapshot of existing logical volume to save a backup of current volume state.