Making a new FreeNAS build... moving from 4TB to 6TB drives

[hungarianhc]

Hi there!

I'm just about ready to pull the trigger on getting parts for a FreeNAS build to replace my Synology + MiniPC (Plex Server) combo. However, I wanted to discuss upgrading from 4TB to 6TB drives, once available / supported.

I plan on creating a vdev of Raid-Z2, with 4 disks. With current 4Tb RED drives, that would give me 8TB of usable space. I'm currently running a Raid-5 like system on my Synology with single disk redundancy and 3 4TB disks (also 8TB usable space). I know that the only way to grow a vdev is to swap out all of the drives for larger ones. That's what I think I would like to do...

I'm a bit over half full on my 8TB usable space Synology system. I don't expect it to grow rapidly, but I would like more space. My thinking is that if I build a 4 drive Raid-Z2 FreeNAS box with 4TB drives, I'll have 8TB of space. Once the 6TB drives come out, I'll swap out every drive on the box, and that should give me 12TB usable space with dual disk redundancy on 4 drives.

How easy is it to do this? THANKS!

 

[survive]

Hi hungarianhc,

It's perfectly reasonable to do, but first thing I would do is check the price of the 6TB drives. I'm seeing them listed for ~$800.00 right now....I don't know how long I would expect to wait before the drop to something more reasonable. It might be smarter to just start out with six 4TB drives & be done with it.

-Will

 

[hungarianhc]

Great to hear it's perfectly reasonable! Well in terms of pricing, the 6TB drives that NAS owners are likely to be attracted to haven't been released yet, hence my waiting... The current ones you're seeing are the helium filled special enterprise drives. DEFINITELY not worth it in that case. Do I replace them just like I would replace a normal drive if it had failed with FreeNAS? And is there something in the UI I can click to "grow" the vdev after I successfully swap out every single one, once at a time?

 

[cyberjock]

And is there something in the UI I can click to "grow" the vdev after I successfully swap out every single one, once at a time?

If you check out the manual and FAQ for expanding a vdev you'd be able to answer that question for yourself. Step-by-step instructions are included...

 

[hungarianhc]

If you check out the manual and FAQ for expanding a vdev you'd be able to answer that question for yourself. Step-by-step instructions are included...

Thank you, good sir! Looks like page 137 on the manual explains it. If I'm reading it correctly, "autoexpand" is on by default. Thus, if I slowly rotate out the drives for 6TB drives eventually, the zpool will just show more space available once it's all done. Correct?

 

[cyberjock]

Thank you, good sir! Looks like page 137 on the manual explains it. If I'm reading it correctly, "autoexpand" is on by default. Thus, if I slowly rotate out the drives for 6TB drives eventually, the zpool will just show more space available once it's all done. Correct?

Exactly!

 

[joelmusicman]

It might be smarter to just start out with six 4TB drives & be done with it.

If you have the space/ports available, I'd highly recommend this course of action. To me buying six drives is more cost-effective for the usable space than buying four and losing half...

Let's see, some quick math, assuming 4tb drives are $200:

4 Drive RAIDZ2 = 8TB usable space / $800 = $100/TB
6 Drive RAIDZ2 = 16TB usable space / $1200 = $75/TB


So if you buy the 4 drive setup now and then replace it in a few years...

Let's assume a 6TB drive will cost $300...

$800 existing setup, let's say you can sell the drives for $450 = $350 sunk cost

4 Drive RAIDZ2 = 12TB usable space / $1200 ( + $350 for money lost from other drives) = $129/TB

 

[DataMover]

Let me add some math to the above:

WD Red 4 TB (4000 GB): 184 $ / 4000 GB = 0,046 $/GB, 4 x 184 $ = 736 $
WD Red 2 TB (2000 GB): 109 $ / 2000 GB = 0,0545 $ /GB, 6 x 109 $ = 654 $

So, buying 6 x 2 TB disks, you slightly loose some GB per $ performance. But in the end, you'll end up close to your available space requirements ( 6 x 2 TB RAIDZ2 leaves you approx. 8 TB) and save some money. Beside the fact, that you'll "loose" half of your disks for RAIDz2 redundancy (and I won't step back from RAIDZ2!), if you go buy 4 TB disks vs. 2/6 if you go for the 2 TB ones.

If you are price conscious and have a few more $ in your budget, consider 3 TB drives. Let's add some more magic math:

WD Red 3 TB (3000 TB): 134 $ /3000 GB ) = 0,0467 $ /GB, 6 x 134 $ = 804 $

This setup will give you all the benefits of a 6 disk RAIDZ2 , you pay slightly more, but get available space like in a 4 x 6 TB (expensive) setup. Figures in the EU are comparable.

Hope that gives you more inspiration ;-)

 

[hungarianhc]

I can afford an extra hundred dollars here or there, but I'd like to keep power consumption and NOISE down to a minimum. I live in an apartment where the FreeNAS box is going to be relatively exposed, and I want noise to be at a bare minimum. That's why I like the 4 drive setup. It gives me 8TB usable space in the immediate future, and when I get closer to filling it up, it's easy for me to swap out all the drives and move up to 12TB usable space... Plus I then have extra drive bays so I can do something like add a 2-disk Raid1 vdev in the future for non-critical data, maybe for example my btsync folders across all my machines, etc.

 

[cyberjock]

You are far far better off building the system with the total number of disks you plan to use for the forseeable future. Adding a 2 disk RAIDZ1 vdev, while doable, means you pay double the price for the same disk space whereas you might get it for actual price if you are already committed to a RAIDZ2.

 

[hungarianhc]

You are far far better off building the system with the total number of disks you plan to use for the forseeable future. Adding a 2 disk RAIDZ1 vdev, while doable, means you pay double the price for the same disk space whereas you might get it for actual price if you are already committed to a RAIDZ2.

Yah but I just threw that in there - I don't see myself getting to 8TB for a while... and then 12TB will be plenty when I swap in the 6TB drives.

 

[cyberjock]

I just realized I had a typo.. I said RAIDZ1 when I meant RAID1