Bug 1613855

+++ This bug was initially created as a clone of Bug #1590967 +++

Description of problem:

When a VDO volume is used as a storage domain, the user needs to be presented with the space savings that he/she is getting

Version-Release number of selected component (if applicable):
4.2

How reproducible:
NA

Additional info:
Space savings should be presented at the brick level as well as the gluster volume/storage domain level

--- Additional comment from Denis Chaplygin on 2018-06-14 04:30:17 EDT ---

What should we do in case same VDO volume is used for several storage domains?

What information should we provide in case of (multiple) vdo-thinp layers?

--- Additional comment from Sahina Bose on 2018-06-15 14:22:46 EDT ---

(In reply to Denis Chaplygin from comment #1)
> What should we do in case same VDO volume is used for several storage
> domains?
> 

I think the same space saving can be reported.

> What information should we provide in case of (multiple) vdo-thinp layers?

Adding Dennis for inputs.

--- Additional comment from Dennis Keefe on 2018-06-15 14:39 EDT ---



--- Additional comment from Dennis Keefe on 2018-06-15 18:18:41 EDT ---

Savings for 2.0
Cockpit will display the VDO savings per node. See attachment.

Savings for 2.0+
Storage Domain

Each storage domain should display the storage savings by averaging each
VDO's volume savings on each gluster's volume bricks.

example:
the brick for vmstore on host-rhhi1 (/dev/sdb)
has space savings of 49% (vdo command: vdostats --hum)

the brick for vmstore on host-rhhi2 (/dev/sdb)
has space savings of 57%

the brick for vmstore on host-rhhi3 (/dev/sdb)
has space savings of 87%

(49+57+87)/3 = 64% space savings

64% space savings should be displayed for the storage domain after "Guaranteed Free Space" and before "Description" 
--------------------------------

Savings for 2.0+
Dashboard

The Dashboard could show the savings either in the storage "circle" as part of the ring or just as text in the center of the 
ring.  I would normally say that the savings would be green, but that is used already, so blue might work.  The savings 
here should report the savings for the cluster not just per storage domain.  

The stats can come from either VDO manager by using "vdostats --verbose" 
Command: vdostats --verbose|egrep "logical blocks used|physical blocks used"

  data blocks used                    : 17275885
  logical blocks used                 : 33712693

Or from sysfs

Sysfs does not hold a percent savings, which means you have to calculate it yourself.
 
1. capture the output of /sys/kvdo/<vdo volume name>/statistics/{logical_blocks_used|physical_blocks_used}
2. add the physical blocks used for all volumes in the cluster together
3. add the logical blocks used for all volumes in the cluster together 
4. subtract the total logical blocks used by total physical blocks used (this is the total number of blocks saved by VDO)
5. then divide the total saved blocks by the total logical blocks, multiplied by 100 to get the savings percent


ls /sys/kvdo/vdo_sdb/statistics/|egrep "logical blocks used|physical blocks used"
logical_blocks_used
data_blocks_used

cat $(ls -d /sys/kvdo/*/statistics/*|egrep "logical_blocks_used|data_blocks_used")
33712680
17275871

Math
33712680 - 17275871 = 16436059  (saved blocks)
16436059 / 33712680 = 0.4875 *100 = 48% (savings percentage)
0.4875 *100 = 48%