Used space displayed wrong at zvols?

[Scampicfx]

Hey guys,

i configured two zvol... one zvol is going to be boot device for esxi host, second zvol will be used as datastore for vms...
When looking at this picture, I'm wondering, why after creation of the highlighted zvol, a usage of 44% is displayed:

The manual says, one should not use more than 80% of the space. The san-volume consists of two mirrored 8 TB HDDs. 10 GBytes are assigned to boot zvol, whereas the remaining 80% percent of 7.0 TiB are assigned to data zvol (5.6 TiB). However, there is no data on this zvol. So why is a usage percentage of 44% displayed?

The drives are using native 4k sectors. The block size of both zvols is 16K (by default).

 

[SweetAndLow]

Zvol probably wasn't created with the sparse option. I think that an option you can choose.

Sent from my Nexus 5X using Tapatalk

 

[Scampicfx]

I didn't check this option. I'm just wondering why a usage of 44% is displayed, although nothing is written to this zvol...

Just to be sure: Is it correct to assign only 80% of the volume capacity to zvols in total? And as far as I remember, each zvol may only be used up to 50% capacity to avoid performance bottlenecks?

 

[SweetAndLow]

I didn't check this option. I'm just wondering why a usage of 44% is displayed, although nothing is written to this zvol...

Just to be sure: Is it correct to assign only 80% of the volume capacity to zvols in total? And as far as I remember, each zvol may only be used up to 50% capacity to avoid performance bottlenecks?

It all depends on your performance needs. For consistent performance keep your pool under 60% full. Zvol fullness doesn't matter to my understanding.

It shows 44% full because that zvol is now using that much specs. The fact that it's empty doesn't matter much it just means nothing else on your pool can use that space.

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