Basic Questions on FreeNAS and ZFS

[nzwogboy]

I am looking at a NAS solution and was considering QNAP but am now considering FreeNAS but have some basic questions to confirm what I think FreeNAS can do.

1. I want to start off with only 2x 2TB drives using RAIDZ1 (I think), and then want to be able to add more 2TB Hard drives as required up to a max of probably 4-5 x 2TB HDD (and as funds allow). Is this possible and will it act similar to a RAID5, ie when I ad the 3rd 2TB HDD will I have ~4TB usable space, and when I add a 4th will I have 6TB usable space? If this can happen is it pretty straight forward, is this what the "Auto import Volume" function is for?

2. Down the track when I have 4x 2TB hdd installed and they are nearing there limit, can I then replace all drives (1 by 1 obviously) with bigger HDD's assuming 6TB drives or something are the norm then, allowing much more disc space eg replace with 4x 6TB to allow ~18TB storage with 1x6TB as parity??

3. I am planning to run FreeNAS on an 8GB USB stick. If the USB drive dies, can I install FreeNAS on a new USB stick and recover my data on the ZRAID?

4. Can you have 2x USB sticks mirrored running the FreeNAS OS, so if one died it would still work? This is not really necessary if question 3 is possible.

5. I read in another post that you could shift your USB stick (running FreeNAS) and the HDD's to new hardware, does this mean that if the motherboard dies that you can just replace it and everything will be fine?

Basicly I am wanting to see what the weak parts are hardware wise and what the upgrade options are.

And yes I do understand that you don't actually get 2TB or usable HDD space from a 2TB HDD, just trying to make the calculations easy Thanks for any help in advance.

 

[ProtoSD]

nzwogboy,

1) You need a minimum of 3 drives for raidz, if you add more disks later they can't be added to that original pool of 3, you would have to create another pool. It doesn't really work the way you're thinking and still get the raid 5 redundancy. If you want raid 5 with 4 or 5 disks, you need to create it that way from the beginning. Auto Import will let FreeNAS import a previously created pool, like for example your Flash Drive died and you created a new one, then you would Auto Import your pool.

2) Yes, you can replace your drives one by one later and after the last one is replaced expand your pool.

3) Yes, if your flash stick dies, you can still access your data again by importing the pool. There's not really any point in running it on an 8GB flash drive as you can't use the leftover space for other stuff.

4) I suppose there is some way you could mirror your flash drives, but it's not a standard feature of FreeNAS, so NO, not without some type of hack.

5) Yes, if your motherboard dies you are supposed to be able to do what you said. You'd probably have re-import your pool(s) again since the device names would probably change.

Does anyone else want to add to or clarify my answers? ;)


Actually, if you're familar with VMware you could create a virtual machine and some virtual mini disks to experiment with.

 

[nzwogboy]

Thanks for your help protosd, you have cleared that up for me. I do like the idea of raid migration (it is the main reason for looking at the QNAP/Drobo products), but the fact that I can use my existing hardware and just need to purchase the HDD's is a big plus for using FreeNAS.

I have been playing with FreeNAS using a Virtual VMware, and it looks nice, was extremely easy to install.

In regards to the 8GB flash drive I thought that that was the recommendation? If it is between a 4GB and 8GB the price is marginal anyway. Now this leads me to a different scenario...

I currently have a Athlon 64 X2 5200+ CPU based PC with 4GB ram, descent power supply all in good condition, that I may end up using (was looking at getting the HP ProLiant MicroServer). I have ear marked this PC for other tasks though, so is it possible/recommended to run FreeNAS as a Virtual OS. If this is the case, I would upgrade the PC to have 8GB or 16GB (cant remember if I have 2 slots or 4) DDR2 RAM. Allow 4GB (or 8GB if have 4 slots) RAM for the FreeNAS and have 4x2TB HDD for the FreeNAS storage Pool. If you can run the FreeNAS as a virtual what is the best way to go about it? What virtual server software should I use? Do I still have FreeNAS on a USB stick? Is it even possible? I want to be running at least a Windows 7 Pro OS on this PC as well.

Not too sure if I you will understand what I am saying, but I guess a good start would be: Is it recommended to run FreeNAS as a Virtual OS other than for testing?

 

[ProtoSD]

Yes, it's possible, I've heard of it being done, but I don't know the details. I'd have to let someone else answer this for you.

 

[matthewowen01]

1. minimum disks for raidz is actually 2 (n+1). only reason to do this is to have 2 disks that contain different data. it is Impossible to expand a raidz(2) vdev, you can't have a 4 disk raidz and add 2 more disks to make a 6 disk raidz. you can add new vdevs to a pool, but they should be of the same vdev type. here is a brief description of the difference of a vdev and a pool. You could easily start with 2 disks in a Mirror (not a raidz), then add 2 more disks in a mirror, then 2 more later on. that's possible and a pretty good solution to slowly growing your storage.

2. you can replace disks in a vdev, one by one to increase the total size of the vdev. if you start with a vdev with 2 TB drives, then a few months down the road when the 6 TB drives come out, you can swap one out, let it resilver, then do the next and the next until they are all swapped, change some settings, export import and you've got your extra storage. you're expanding the vdev, which intern expands the pool. it's pretty simple but you should ask for advice before you start.

3. to make things a bit quicker, backup your settings before hand. but not having a backup will not limit your recovery.

5. the original release of freenas 8 has a bit of trouble with disks moving around, but it's possible with a bit of work. afaik all the betas have fixed this issue.