FreeNAS works with Raid or Replaces it?

[tethlah]

So I'm going to be starting with 4 2Tb drives for my NAS. My question is does FreeNAS actually handle the raid itself or does it do something else?

My concern is that I plan on expanding form 4 2Tb drives to 12 2Tb drives over time. But I don't want to have to rebuilt my raid as I won't have any other devices to store the data on when I upgrade. So over time can I keep adding 2 Tb drives and increase the total space on the array (or is it even a RAID?).

I'm just confused because when I was talking about this to a friend he said "Don't do a raid man, just use ZFS and FreeNAS." Before I would just get a RAID card, connect all my drives to the card, and handle the raid that way. But with this, how should I go about connecting 12 data drives to the motherboard if not using a raid card, and will I actually be able to expand my array while the data is still in the array without causing problems? I'll never drop the size of the array, only increase it. But I still want to have some safety like what a RAID 6 or 5 offers.

 

[Bidule0hm]

FreeNAS use ZFS and ZFS is your RAID controller ;)

My concern is that I plan on expanding form 4 2Tb drives to 12 2Tb drives over time. But I don't want to have to rebuilt my raid as I won't have any other devices to store the data on when I upgrade. So over time can I keep adding 2 Tb drives and increase the total space on the array (or is it even a RAID?).

You can't do that. If you use striped mirrors you can expand 2 drives by 2 drives. If you use RAID-Z1 it's 3 by 3 drives, 4 by 4 drives with RAID-Z2 and 5 by 5 drives with RAID-Z3.

Please read Cyberjock's ZFS guide, the link is in my signature ;)

 

[tethlah]

When I get home I'll be reading that thanks :)

What about a controller? Most likely I'd just go ahead and add drives 3 at a time starting with 2 3 drive sets then (6 drives total) and down the line add new sets 3 at a time until my drives are full.

But what about the controller? I obviously don't have 12 sata spots on the mobo (not to mention adding the OS drive.

 

[solarisguy]

[...]
But what about the controller? I obviously don't have 12 sata spots on the mobo (not to mention adding the OS drive.

A simple additional SATA controller needs to be deployed, like
Avago SAS 9211-8i Host Bus Adapter (LSI is now Avago, and new firmware gives the product the Avago label).

It does not need to be the original, it could made by somebody else using the same chip, for example
http://www.silverstonetek.com/product.php?pid=523

The catch? You download from Avago the firmware that allows direct access to the drives (that firmware does not even allow for the hardware RAID). Read the earlier forum posts for more details.

Your real problem is your idea of having one single volume of data, that keeps growing. If you are comfortable with at least two volumes, that would be much easier. Or if you could deploy 6 or 8 drives that are 6TB each, that would be much, much, much simpler...

P.S.
Your OS drives are going to be two (mirrored) USB memory devices attached to USB 2.0 ports.

 

[tethlah]

What about doing two 6x volumes? At 2Tb a piece that would give me 2 8tb volumes for a total of 16 right?

Really, on a USB stick? Can't I just take a couple extra sub 200gb drives that I have and mirror those and put them on the mobo? Why USB?

 

[Bidule0hm]

No, you'll get 8 TB because you use half the drives for parity.

You can, it'll just take 2 SATA ports, but you definitely can.

 

[solarisguy]

Given the same amount of storage, when using 6TB drives and not 2TB drives, your drives would dissipate almost one third of heat and would be generate less noise.

 

[danb35]

Can't I just take a couple extra sub 200gb drives that I have and mirror those and put them on the mobo?

Sure, you can, but it'd be a waste of space, power, and SATA ports. FreeNAS is designed to be installed to, and run from, a small (8-16 GB) flash device--USB stick, SATA DOM, or small SSD. You can't use the boot device for storage. But you can install it on whatever you want, as long as your machine will boot from it and the capacity is adequate.

 

[solarisguy]

[...] Really, on a USB stick? Can't I just take a couple extra sub 200gb drives that I have and mirror those and put them on the mobo? Why USB?

Why USB?

In the default configuration, these two USB memory devices would operate in the read-mostly mode.

 

[danb35]

these two USB memory devices would operate in the read-mostly mode

Not any more. In 9.2.x and prior, yes, the boot filesystem was mounted read-only, but in 9.3, it's a live ZFS pool. There won't be much writing going on most of the time, but it isn't read-only.

Never mind, I obviously misread your message as saying "read-only" rather than "read-mostly".

 

[tethlah]

well, it wont be a waste of sata ports as all the sata ports on the mobo are free to be used anyway so I may as well just use something I already have.

And you're saying that if I install 24 tb of drives with Raid Z2 i'll only get 8tb of space??? No way I'll ever use Z2 then.

 

[danb35]

And you're saying that if I install 24 tb of drives with Raid Z2 i'll only get 8tb of space???

No. The worst you'd do is 12 TB, but it depends on the size of the arrays. If you do six-disk arrays (say, 6 x 4 TB disks), you'd have 2/3 of your total capacity usable. With eight-disk arrays, you'd have 3/4 of your total capacity usable.

 

[danb35]

No, you'll get 8 TB because you use half the drives for parity.

How are you using half the drives for parity in six-disk vdevs? I guess if you do RAIDZ3, but that wasn't what he was suggesting.

 

[solarisguy]

No. The worst you'd do is 12 TB, but it depends on the size of the arrays. If you do six-disk arrays (say, 6 x 4 TB disks), you'd have 2/3 of your total capacity usable. With eight-disk arrays, you'd have 3/4 of your total capacity usable.

Actually closer to 11 if you want to stay below 80%... So yes, having more disk in a vdev makes you "loose" less space.

 

[Bidule0hm]

I thought that he was talking about doing 6 mirrors... I read a bit too fast I guess :)

 

[Deleted47050]

Whatever you choose to do, make sure you choose the right RAIDZ level right from the beginning, as i don't think you can move from RAIDZ1 to RAIDZ2 without rebuilding your pool.

(I am mentioning this because it looks like you haven't really decided how many drives to start with yet)

 

[tethlah]

This makes no sense. Originally someone said you have to have either 3, 4, or 5 disk arrays. I saw that 3 was for Z1 (2+1) and 4 was for Z2 (2+2). Then someone else said you can do a Z2 in 6 (4+2). So I decided to dothe Z2 in 6 drives and do 2 arrays (I guess striping the arrays? no clue this is way more convoluted that a simple raid array).

Now people are saying that I'll loose 50% of the space, some are saying as little as 35%.

Seriously? How variable is this, is it even worth trying to get into? The entire thing seems really uncertain when it comes to how it's actually supposed to work because I have yet to get the same answer out of 2 different people. I just want to put all my media in a central server that has some fault tolerance without having to spend 2-5k to do it. (and no, I'm not going above a 2Tb drive because that completely defeats the whole affordability thing, I don't need 12 6Tb drives).

 

[tethlah]

Whatever you choose to do, make sure you choose the right RAIDZ level right from the beginning, as i don't think you can move from RAIDZ1 to RAIDZ2 without rebuilding your pool.

(I am mentioning this because it looks like you haven't really decided how many drives to start with yet)

I started off with 4, but then someone said I had to do my upgrades in the same drive number, so I decided on doing 3 at a time, but then another article on here says Z1 is stupid to rely on unless you want to loose all your data, but doing a raid 6 level array where you loose half your drives makes no sense to me, so I decided to go with 6 (4+2) and that I would just upgrade it later with 6 more drives (right now I have 3.7Tb of media that I need to put somewhere, so going with anything that gives me less than 6Tb of storage makes no sense right now).

 

[gpsguy]

If you go with 2 - RAIDz2 vdevs with 6x2TB each, that will yield about 14TiB of usable storage.

RAIDz1 isn't recommended, so using vdevs with only 3 drives is out (for your use case).

 

[Bidule0hm]

No, it's not variable. It's just that I read too fast (I interpreted "What about doing two 6x volumes?" as 6 mirrors of 2 drives) so I gave an answer for mirrors, not RAID-Z2.

With a mirror: you need 2 drives and you use 1 drive for parity

With RAID-Z1: you need minimum 3 drives and you use 1 drive for parity

With RAID-Z2: you need minimum 4 drives and you use 2 drives for parity

With RAID-Z3: you need minimum 5 drives and you use 3 drives for parity

The recommended maximum number of drives per vdev is 11.

You can have as many vdev as you want per pool.

The usual configurations are 3 drives RAID-Z1 and 6 or 8 drives RAID-Z2.

NB: using RAID-Z1 with drives bigger than 1 TB isn't recommended, see the link "RAID-Z1/RAID5 isn't recommended" in my signature for more details.