FreeNAS not using entire disks

[MR. T.]

Hi,

I have been trying to test a few options for a home NAS, and i was thinking of setting up freenas.

I have been testing this on a virtual environment before going to spend large amounts of money in hardware, and have been surprised how good freenas is.

That being said... i have a big problem:
I created 6 2gb disks (virtualdisks but is for testing only so makes no difference), and created a raidz volume with 5 of them.
At this point i expected to get a volume with 8gb (4x2gb data +1 parity), but the volume was only 4gb. I ignored this and thought i had messed up somewhere, so i created it again and had the same behavior.

so i deleted the disks one by one and replaced them with 5gb disks (so i could test if the volume would magically grow when all disks were substituted) and it grew, but again to half the expected volume size.

I deleted the volume and when i come to recreate the volume i get:
5x1x5.4 GB
Capacity: 12.00 GiB

a single disk as stripe shows:
1x1x5.4 GB
Capacity: 3.00 GiB

On the first case i expected 5*5.4 (raidz) to be capacity 20gb
On the second one i expected the full 5gb to show as capacity.

There might be a very obvious reason for this but i cant think of one. I googled and looked through the forums for hours and came up with no explanation for this.

This is the only think preventing me from going to buy the hardware for this... if i lose more than half of the disks capacity it's not a good solution for me.

Thank you in advance for your answers.

 

[Bidule0hm]

FreeNAS use 2 GB of swap space on each drive so with very small drives you have to include that.

 

[pirateghost]

Hmm. I wonder what the documentation says:
http://doc.freenas.org/9.3/freenas_install.html#virtualization

 

[MR. T.]

Hi.

BiduleOhm, i must have missed that from the documentation, and that completely explains the weird behavior i was getting.
Thank you very much. I'll probably go and build a freenas machine then.

pirateghost, i do not understand what you are trying to point out. I read that before and it says that using on a virtual environment for testing purposes is perfectly fine.
also says the OS disk needs to be at least 8gb (mine is 32gb) and the data disks need to be at least 4gb, hence the 5gb virtual disks.

In any case the simple but excellent post from BiduleOhm answered the question.

Thank you

 

[pirateghost]

Hi.

BiduleOhm, i must have missed that from the documentation, and that completely explains the weird behavior i was getting.
Thank you very much. I'll probably go and build a freenas machine then.

pirateghost, i do not understand what you are trying to point out. I read that before and it says that using on a virtual environment for testing purposes is perfectly fine.
also says the OS disk needs to be at least 8gb (mine is 32gb) and the data disks need to be at least 4gb, hence the 5gb virtual disks.

In any case the simple but excellent post from BiduleOhm answered the question.

Thank you

http://doc.freenas.org/9.3/freenas_intro.html#storage-disks-and-controllers

From the documentation:

If you will be using ZFS, Disk Space Requirements for ZFS Storage Pools recommends a minimum of 16 GB of disk space. Due to the way that ZFS creates swap, you can not format less than 3 GB of space with ZFS. However, on a drive that is below the minimum recommended size you lose a fair amount of storage space to swap: for example, on a 4 GB drive, 2 GB will be reserved for swap.

In other words:
You should read through the docs to familiarize yourself with the system