why can i create mutiple datasets using same disk space

[Clawhammer]

Hello together,

sorry iam new to this and iam trying to understand why i can create mutiple datasets using the same disk space. This is very confusing to me. I expected that the disk space gets splitted by every additional dataset, but i can create a few and still use the same entire disk space.

What is the purpose of that? Thanks for help!

 

[Patrick M. Hausen]

The disk space is managed dynamically. There is no such thing as "partitions" in ZFS. You might want to read the ZFS Primer to learn about some basic concepts:

ZFS Primer

Background information about the Zettabyte File System (ZFS).

www.truenas.com

 

[Clawhammer]

Ok, i read the primer, so its just not necessary to limit the space for it, ok. But still not sure why i want to create more then one dataset.

 

[sretalla]

still not sure why i want to create more then one dataset.

Different recordsize, different snapshot timings/retention, different encryption, different quotas... long list of other dataset properties and their features...

 

[Clawhammer]

I do it for different features... thats something i can work with it. Thanks!
When it comes to sharing smb shares, are there any cases i have to consider more then one datasets (for user managment)?

 

[anodos]

You can also set up different snapshot schedules for different datasets.

That said, I personally prefer a flat heirarchy for datasets. Dataset names (including snapshots) are limited to 256 characters. The full string "dozer/share/my/sub/dataset" all counts toward the name limitation. Snapshot names are also limited in this way "dozer/share/my/sub/dataset@thisreallylongtimestamp0005" also cannot exceed 256 characters.

So something like:
dozer/archive
dozer/accounting
dozer/media

and so forth.

By using multiple datasets you have more flexibility regarding how you manage replication. Perhaps you want dozer/accounting to go to a different backup server than dozer/archive.

 

[anodos]

When it comes to sharing smb shares, are there any cases i have to consider more then one datasets?

I always create one dataset per share.

 

[sretalla]

When it comes to sharing smb shares, are there any cases i have to consider more then one datasets (for user managment)?

Perhaps you might want to do auditing on one share and not the other...

 

[Clawhammer]

ok, thank you. That helped me a lot understanding that!