strange storage utilization view

[Thomymaster]

Hi

I have a basic question, today i looked at the storage utilization view of my FreeNAS box.

The zpool2 consists of a mirror of 2 128GB SSDs

cifs_bilder is a dataset with quota and reservation set to 100GB
cifs_bwin3c is a dataset with quota and reservation set to 2GB
zvol3 is a zvol created with a size of 20GB

Now can somebody explain to me the attached image?

1. From my windows box i know that the 2 values for "Available" are correct. But where do the values for "Used" come from?

2. Regarding the zVol i don't understand the values for "Available" and "Used" as well. It is a ESXi datastore and completely empty.


Are these issues a bug?


Cheers
Thomy

 

[willnx]

To save cyberjock the time, i'll just link his response when I brought this up.

TL;DR - Yup... It's a thing and we know...

Technically it's not a bug. It technically has to do with how free space is calculated for pools and datasets. Datasets are actually their own filesystem, so the boundaries make things look non-obvious. There are plans in the works to have this make a little more logical sense to the common reader, but you will still have to understand where the boundaries are and how it all works. ;)
To make things worse things like quotas, snapshots and reservations do not show up on that particular list, but they are there and they do take up space.
In essence, that gives you only the broadest info, and only if you understand it all. If you don't then it looks totally jacked up. There's been tons of threads on this topic and a bug ticket already exists to make this a little more "real" for casual readers.

 

[cyberjock]

There ya go. Thanks for answering for me willnx. :)

If you don't understand it, those numbers will only confuse the living hell out of you. If you do understand them, then they make sense. As ZFS was designed as a "humongous scale file-server file system" it lets you do all sorts of things you've probably never been introduced to. Things like file systems inside file systems (totally different from doing partitions), snapshots, quotas, reservations, etc. So you have to understand all of the nuances of ZFS or the numbers mean nothing. No matter how much you try to change things, they will *never* be understood to the "dumb" reader that doesn't understand all the nuances.