Short FreeNAS Question

[DatScrubBoi]

I'm learning how FreeNAS works, but just wanted to clear something up.

I understand that the drives in a VDev can't be changed, and that VDevs make up the ZPool.
I understand that if a VDev fails the entire ZPool fails and all data is lost.
And I understand that not having redundancy and losing a striped drive in a VDev will cause that VDev to fail.
However, if the RAID array is setup for redundancy there is a way to save the data, and I get that there is a way to rebuild data from something like RAID6 (Z2) but I'm not going to get into anything that complex with my first build.

If there are just two drives that are RAID 1 and mirrored in a single VDev in the ZPool, and one of them fails, what happens?
Does the NAS stop working or will it allow you to use the drive that isn't dead until the other is replaced?
Is it as simple as replacing the drive and there's an option in the web GUI or a command to rebuild the data from the good old drive to the new one?
I'm not very familiar with RAID in general, in a simple mirrored setup like this can you just connect the drive to a normal desktop and extract the data? Or does it HAVE to be read in a RAID array connected to another replaced drive?

[DatScrubBoi]

Looking into it a little more, it seems that many data storage centers don't use RAID 1 at all, and just setup their systems to completely mirror independent drives, drives that could easily be accessed from any machine and duplicated. RAID 1 adds a layer of data on top and a method of reading that will apparently keep you from just plugging in a surviving drive and extracting it, and many people for whatever reason experience data loss in a failed RAID 1 array, is there any way to setup freenas to just completely duplicated the data on the drives without dealing with RAID at all? And if there is only a single drive in a FreeNAS ZPool can you just plug it into another machine and it will work or does FreeNAS itself do something to the file table or whatever else that makes it unreadable?

[Electronics Wizardy]

5 hours ago, skylerskinner said:

the drives in a VDev can't be changed,

What do you mean?

 

you can make a single drive into a mirror, or replace a drive, or expand it by replacing all drive with bigger ones. raidz expansion is comming soon.

 

5 hours ago, skylerskinner said:

what happens?

Nothing, it warns you and works like nothin happened.

5 hours ago, skylerskinner said:

Is it as simple as replacing the drive and there's an option in the web GUI or a command to rebuild the data from the good old drive to the new one?

Yep, zpool replace in the command line or there is a way in the gui aswell.

 

5 hours ago, skylerskinner said:

in a simple mirrored setup like this can you just connect the drive to a normal desktop and extract the data?

If you have the minnium number of drives(1 in this case) and a supported system(linux or freebsd with zfs) it will work. You can't access these drives in windows though

 

5 hours ago, skylerskinner said:

is there any way to setup freenas to just completely duplicated the data on the drives without dealing with RAID at all?

Yea thats what backups are for, use rsync on a external hdd.

 

The thing is raid isn't a backup, its there for uptime. It lets you keep using your nas with a drive drives like nothing happened. You still need backups to keep your data safe as there are many other ways for the data to be lost even with raid.