Disabling automatic RAID-Z

[Kingstone]

Hi, I just installed freeNAS on an ML110 server, had no raid configured on the server controller, but suprisinlgy it automatically picks a RAID-Z by default. How do i disable this and get maximum capacity on FreeNAS 11.1 U7

 

[danb35]

it automatically picks a RAID-Z by default.

Why is this surprising? FreeNAS assumes you care about your data. If you don't, you might find a different OS better suited to your needs. But still, you can easily set the pool layout to stripe or anything else you want.

 

[danb35]

Please don't cross-post:
https://www.ixsystems.com/community/threads/disabling-raid-z.74469/#post-516778

 

[Chris Moore]

What do you want? What are you thinking about when you say "maximum capacity" because that's not a level of parity under ZFS.

 

[jgreco]

[Mod note - merged superfluous thread back into New to FreeNAS? thread]

 

[Kingstone]

What do you want? What are you thinking about when you say "maximum capacity" because that's not a level of parity under ZFS.

So the ZFS feature can't be disabled, I'll just have to do with the RAID-Z?

 

[Kingstone]

What do you want? What are you thinking about when you say "maximum capacity" because that's not a level of parity under ZFS.

I have 8TB raw, but on installing FreeeNAS, its down to 3.8TB, which means half is gone. For my setup I really need the whole 8TB, how do i get this?

 

[danb35]

So the ZFS feature can't be disabled, I'll just have to do with the RAID-Z?

No, ZFS can't be disabled. Yes, RAIDZ can be disabled. Did you read my post?

For my setup I really need the whole 8TB, how do i get this?

If you need 8 TB of available storage, you need at least 10 TB of disk space. Then set the pool to be striped, as I told you above. But seriously, there's lots of good documentation that it doesn't seem you've read. I'd strongly encourage you to read it before you paint yourself into a corner with your setup.

 

[Chris Moore]

I have 8TB raw, but on installing FreeeNAS, its down to 3.8TB, which means half is gone. For my setup I really need the whole 8TB, how do i get this?

You need larger drives. If you actually need to use the entire 8TB, you can't get there at all with only 8TB of mechanical drives in FreeNAS. Even if you set the drives up as a stripe with no parity, you have ZFS using part of the space for checksum data so you can never have the entire 8TB for your data.
In addition to that, you should never fill any ZFS file system above about 90%. The performance of the files system tanks above 90% and you start getting a warning about that at 80%.

Edit. It is possible, if the data is highly compressible, you might be able to fit 8TB of data in the space that is available. Not likely, but possible.

 

[Chris Moore]

So the ZFS feature can't be disabled, I'll just have to do with the RAID-Z?

The reason to use FreeNAS is so you can have ZFS. If you don't want ZFS, you are in the wrong place. Sorry.

 

[jgreco]

The reason to use FreeNAS is so you can have ZFS. If you don't want ZFS, you are in the wrong place. Sorry.

Approximately correct. Also worth noting, if there's a read error and ZFS can't rebuild your data from redundancy, your data is at (probably mild, possibly not) risk of loss. This can be a serious issue if pool metadata is corrupted. Running without redundancy is Bad.

 

[danb35]

This can be a serious issue if pool metadata is corrupted.

...which is why ZFS keeps at least two, and as many as six, copies of all metadata. Even in a single-disk pool.

 

[jgreco]

...which is why ZFS keeps at least two, and as many as six, copies of all metadata. Even in a single-disk pool.

Which is small comfort if that doesn't survive due to a failing disk, etc.

 

[danb35]

Which is small comfort if that doesn't survive due to a failing disk, etc.

Agreed. But a single-block read error shouldn't kill your pool (which is why I'm not 100% on board with the "RAID5 is dead" argument as applied to ZFS).

 

[jgreco]

Agreed. But a single-block read error shouldn't kill your pool (which is why I'm not 100% on board with the "RAID5 is dead" argument as applied to ZFS).

Fine, but it was always BS with the "RAID5 is dead" argument too, because typically most filesystems do have corruption recovery tools. ZFS does not.

File data is damaged in either case (ZFS/non-ZFS+RAID5) anyways.

But more worrying, the statistical reliability of a single hard drive is not that great, and a pure stripe situation reduces pool reliability significantly. @Nick2253 ran the numbers some years ago and came up with this:

So if you have four drives, striped together, and your drive AFR is 3%, you amplify the AFR for a pool AFR where you run an 11.47% AFR. See the linked article for the deep dive.

 

[Evertb1]

Like @Chris Moore I can't help but wonder what the rationale was for OP to make the choise for FreeNAS. Four years ago I left Windows Home server for FreeNAS with as main reason the ZFS file system. I made that choise after a lot of reading and not just on the FreeNAS forums. If ZFS and al its properties is not for you then there are other (free) possibilties for your storage. Though no mather what file system you end up with, you will always have some overhead and you will never have the full capacity of your disks for storage.

 

[Evertb1]

But more worrying, the statistical reliability of a single hard drive is not that great, and a pure stripe situation reduces pool reliability significantly. @Nick2253 ran the numbers some years ago and came up with this:

Thanks for pointing to that thread. Usefull information.