question: 3 way mirror redundancy

[diversity]

LS,

Please forgive my ignorance as a newcommer to the freenas field.

My intend is to have a 3 way mirror so that 2 of the 3 drives can fail at once without loosing any data.

zpool status (pool name obfuscated);

Is this properly configured to be able to have 2 drives fail at once and not loose any data?

If not then is there a guide or could you please point me into the right direction?

I welcome any reaction but to rest everybody assured regarding the 'not loosing any data' I intend to have 2 extra of these setups spread across the globe that are in sync. This question is in context of the 3 disks I have locally.

Kind regards

 

[sretalla]

You appear to have a 3-way mirror correctly configured from the zpool status output in the first image.

 

[diversity]

@sretalla Thank you for your response. Did the second image I included had any usefulness into you assessment?

The reason I ask because I am still struggling with the conceptual difference between the different types (e.g. dataset, zvol if not more)

Is it appropriate, adhering to the forum rules, for me to follow up with?:

As far as I have figured this basic scenario of a 3 way mirror is unavailable in MS REFS. That realization is what triggered me to double check my current approach and ask the original question. Is there an explanation why ZFS can do this by default and REFS persists its not possible/available/supported?

 

[mistermanko]

The reason I ask because I am still struggling with the conceptual difference between the different types (e.g. dataset, zvol if not more)

I can heartily recommend you to have a look at cyberjock's Slideshow for that.

 

[diversity]

@mistermanko Thx, I will check it out.

 

[sretalla]

Is there an explanation why ZFS can do this by default and REFS persists its not possible/available/supported?

REFS is a filesystem, relying on Hardware RAID or OS-provided software RAID (so most likely you can do it if your Hardware RAID supports 3-way mirroing).

ZFS is software RAID and a filesystem working together and does not rely on anything else to determine its features.

 

[diversity]

@sretalla . Thank you for your elaboration.

Further more:
Again my ignorance at play here but I can't get my head around the image below from the slideshow mentioned above:

Also when searching for the term 'dataset' in the presentation below I get 0 results. (this can because of libreoffice missing functionality)

The image below suggests to me that I will need at least 6 drives to prevent a data loss when 2 drives fail. Or am I mistaken between my mirrored setup and the seemingly depicted raid-z2 setup below?

I'll keep struggling just a little while longer before maybe it's perhaps time to hire a local freelancer to sanitize my (intended) setup.

 

[sretalla]

A dataset lives on top of the volume (root dataset) of a pool.

A dataset is a filesystem which can have snapshots, storage limits and quotas applied to it and can be transferred at block level (and replicated) with ZFS commands and can be shared via NFS, SMB, AFP and WebDav.

ZVols are individual "files" which are used as block storage for things like VMs and iSCSI targets. They can also have snapshots taken, but can't present a filesystem to FreeNAS to read or share in the traditional sense. Their contents would be things like an NTFS filesystem for a Windows VM or extfs4 for Linux VMs.

A 3-way mirror is not RAIDZ2, so the points in that picture aren't applicable to your case. I did read somewhere that you can have RAIDZ2 on just 3 disks, but I don't think that's supported in the FreeNAS GUI and would be of little benefit in terms of performance or redundancy over a 3-way mirror.

 

[diversity]

@sretalla Thx again. I'll let it all sink in for a while.