about the deduplication and compression

[am007_yang]

When  i use the Vsan  environment， i  enable the  deduplication and  compression .

I  see the  deduplication and compression result ，and  saving  capacity.

i want to know the  ratio , how to calculate this ratio ？

for example below picture ， the 1.4x , how  to calculate ?

 

[Fouad Sethna]

see the section: Verifying Space Savings from Deduplication and Compression 

https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.virtualsan.doc/GUID-3D2D80CC-444E-454E-9B8B-25C3F620EFED.html

It should give you a guide on how to do that.

[am007_yang]

hi   vFouad

thank you very much , i have learned the doc , now i  understood that how to  calculate the radio of dedup and compress.

 

thanks again .

[TheBobkin]

 , Deduplication savings ratio is calculated based on the amount of space saved minus the overhead costs of using this feature e.g. if you had 200GB of data with only 100GB being unique (e.g. 2x100GB of the same data) and with 20GB of overhead then this would be 1.8x.

 

Couple of points:

Data is deduped per Disk-Group so smaller DGs won't dedupe as well.

Any thick-provisioned or encrypted data won't dedupe.

The more full the DGs the higher the likely dedupe ratio will be.

[am007_yang]

hi TheBokin

thank you very much  reply , and about the deduplication and comression  radio ，I want to confirm whether my calculation method is correct by the following example，If I am wrong, please help correct it . thanks . 

 

Dedup and compression  radio =   30.09GB  be divided by  20.55GB，      The ratio is about   1.46 X  ，

（But the ratio in the screenshot is 1.63x），maybe  my method is incorrect ，help me correct .

 

Used capacity：  20.55GB  =  Actually written  11.97GB +  Reserved  8.59GB

 

Before  dedup and compression：    30.09GB   =  Actually written  11.97GB  +  Reserved  8.59GB   + Saving  10.91GB

 

[am007_yang]

 

all  Vmware expert

about the  deduplication and compression， i  send the picture of the  dedup and compress  form the Vsan Gui . 

i want to get the detail informaton , and please verify it , 

 

thanks you very much.