do not give zfs all your hdd

[cloudfire]

While building my first FreeNAS I stumbled over this :

http://www.freebsddiary.org/zfs-with-gpart.php
It basically explains, that drive sizes vary and if eg. a 4TB replacement for a defective 4TB HDD has just one block less , than it can not be used since it has to be > or = in size. So the author recommends to use partitions for zfs which are a little smaller than the hdd to be safe.

I can not remember that I would have read about this in any beginners guide here. Are there disadvantages in doing so or is this not a real world problem (and why), or did I just miss it out.

I want to use encryption, is there any problem with underlying partitions ?

 

[wblock]

FreeNAS does this by default. Drives are partitioned and have swap space. If encrypted, an encrypted device is created on top of the data partition, then ZFS uses that.

 

[danb35]

It basically explains, that drive sizes vary and if eg. a 4TB replacement for a defective 4TB HDD has just one block less , than it can not be used since it has to be > or = in size.

Aside from @wblock noting that FreeNAS already does this by default, this isn't the case, and hasn't been for some time. Drive capacities are standardized--any 4 TB drive will have the same usable capacity, to the byte, as any other 4 TB drive.

 

[Ericloewe]

Aside from @wblock noting that FreeNAS already does this by default, this isn't the case, and hasn't been for some time. Drive capacities are standardized--any 4 TB drive will have the same usable capacity, to the byte, as any other 4 TB drive.

USB flash drives, on the other hand... Well, the less said the better.

 

[danb35]

Fair enough--USB flash drives aren't even remotely consistent in capacity.

 

[rs225]

ZFS itself also allows for some variation in the block count.

 

[Vito Reiter]

You could do the production environment safe thing and when a drive begins to fail order the same exact drive.