3 questions before I pull the trigger

[TDB]

Hi guys! I'm new here, new to FreeNAS, (not completely) new to ZFS.

Before I pull the trigger and purchase the necessary hardware to run FreeNAS for my home setup, I have 3 questions for which I could not easily find answers:

1. Can I have multiple ZFS pools in the system?
2. In case of boot drive failure (or a need to move the disks forming a pool to different hardware), can I detect the ZFS pool from connected disks/partitions?
   
3. In case of a striped (say, RAIDZ2) or mirrored vdev, what happens if the replacement drive has a slightly lower actual capacity than the existing drives in the vdev? Will the capacity of the whole vdev get adjusted down (assuming there is free space) or will my new disk be rejected? Is it a good idea to work with 99% sized partitions instead of disks for that reason?

Thanks in advance for your help!
M

 

[anodos]

Can I have multiple ZFS pools in the system?

Yes

In case of boot drive failure (or a need to move the disks forming a pool to different hardware), can I detect the ZFS pool from connected disks/partitions?

Yes. Just follow steps in the FreeNAS handbook to import your zpool.

In case of a striped (say, RAIDZ2) or mirrored vdev, what happens if the replacement drive has a slightly lower actual capacity than the existing drives in the vdev? Will the capacity of the whole vdev get adjusted down (assuming there is free space) or will my new disk be rejected? Is it a good idea to work with 99% sized partitions instead of disks for that reason?

The swap partition on your disks is there to prevent this problem from happening. FreeNAS takes care of this for you.

 

[depasseg]

1. Can I have multiple ZFS pools in the system?

Absolutely! I've got 3 in mine.

2. In case of boot drive failure (or a need to move the disks forming a pool to different hardware), can I detect the ZFS pool from connected disks/partitions?

I'm not exactly clear on what your question is asking. But you can easily import a pool into another freenas system (just boot from the USB stick). You can also mirror the Freenas boot device to protect against a boot device failure.

3. In case of a striped (say, RAIDZ2) or mirrored vdev, what happens if the replacement drive has a slightly lower actual capacity than the existing drives in the vdev? Will the capacity of the whole vdev get adjusted down (assuming there is free space) or will my new disk be rejected? Is it a good idea to work with 99% sized partitions instead of disks for that reason?

You can't replace using a smaller drive, but I there are a couple safeguards to prevent this from happening during pool creation.

 

[TDB]

hey, thanks for all the responses!

You can't replace using a smaller drive, but I there are a couple safeguards to prevent this from happening during pool creation.

So even if the new drive is smaller by 1 byte, it can not be used? This would seem like a rather big problem in practice. Is there a way to not use 100% of disk capacity when creating a vdev so that any new disk with same nominal capacity would work as a replacement?

 

[depasseg]

So even if the new drive is smaller by 1 byte, it can not be used

If you use FreeNAS to format the drive, this won't be an issue, because as anodos mentioned, the small swap space can vary, which allows for this variation. If you insist on doing it yourself against the recommendation of FreeNAS, then you would be in trouble down the road, all because of 1 byte.

 

[TDB]

And that answers all my questions! Thanks!!!

 

[joeschmuck]

If you want a pretty much error free boot device, get a small SSD, whatever is cheap on the market or if you have an old one lying around, that will do fine. USB drives as boot devices are unreliable. I personally have not had any issue with a USB drive failing to work but when I did use a USB flash drive, they were all high quality, nothing was cheap, and they are all USB 2.0. Stay clear of USB 3.0 flash drives for FreeNAS, that just some friendly advice. Yes, many people use them but there are a lot of folks who do have problems with them.

As for questions you didn't ask which I think you should do before you "pull the trigger" is:
1) What are you going to use your system for? (think about 1 year down the road)
2) How much storage do you need today? (think realistically and then double it at least because this should last you 3 years at least, and you need to use a RAID calculator so you know the size and quantity of drives you need)
3) Can I add storage later? Yes you can but you cannot add a single drive to increase the size of a pool without serious data risk.
4) How much redundancy should I have? Well that depends on what your system is used for but in general a RAIDZ2 is fine.
5) How much RAM do I need? 8GB is minimum but depending on what you want to do you may need more RAM. If you don't know then make sure you purchase the minimum number of RAM sticks to run your system and leave a few slots open for future upgrades.

Okay, I'm off topic, you never asked those questions but if you asked some basic questions earlier and you didn't know the answers so I thought you might want to ask a few more. I'd hate to see someone purchase either way too much or not enough hardware to meet their needs.

Good luck and please ask questions if you need any help. Also read the user guide from cover to cover at least once, even if you don't understand it, at least it may jog your memory later on down the road.

 

[TDB]

Thank again guys!

I just finished assembling and configuring my server. I went with:
Supermicro A1SRI-2758F-O, 16GB ECC RAM, 16GB USB2 Kingston for boot drive, 4x2GB WD Red in RAIDZ2 (redundant volume), 1x1GB (non-redundant volume for garbage files). Works like a charm.
Yes, I noticed there is 2GB swap space added to each ZFS disk which will cushion the replacement drive if need be.
For the first-time user it was not obvious that you create a VDEV at the same time as you create a pool (volume). Not being able to provide a name for the VDEV separately from the name of the pool was wired. Using terminology that is different from ZFS was confusing too.

My next plan is to figure out how jails work and create my own Amazon Cloud Drive plugin for off-site backups. I'm a software dev during the day, so I guess I can make it happen...

 

[DrKK]

terminology that is different from ZFS

We use terminology that is different?

 

[TDB]

We use terminology that is different?

Yeah. The ZFS tutorial talks about "pool"s, "VDEV"s. Freenas GUI talks about "volume"s.

 

[rs225]

hey, thanks for all the responses!

So even if the new drive is smaller by 1 byte, it can not be used? This would seem like a rather big problem in practice. Is there a way to not use 100% of disk capacity when creating a vdev so that any new disk with same nominal capacity would work as a replacement?

Not a problem. All modern drives actually do have exactly the same size, but ZFS still allows a bit of variance. FreeNAS' variable swap would allow even more.

 

[DrKK]

Yeah. The ZFS tutorial talks about "pool"s, "VDEV"s. Freenas GUI talks about "volume"s.

I guess that's fair. I never noticed it. Aside from "volume" vs "pool/zpool", I don't believe there are any other terminology differences.

 

[gpsguy]

If you haven't already done so, take some time to burn-in your system before filling it with data.

There's a sticky on the forum with suggested steps.


Sent from my iPhone using Tapatalk

 

[DrKK]

All modern drives actually do have exactly the same size

Is that true? Like, a Seagate 4TB NAS, a WD red 4TB, an HGST 4TB NAS, and a Toshiba 4TB desktop drive, all of these will have exactly the same number of bytes of capacity? I'm really skeptical sir, to be honest.