How to upgrade the raid

[dwf2008]

Hi all. I am totally new to this NAS business. A couple of months ago I converted an old pc (intel i5) into my first NAS by adding a couple of wd red 8 tb drives and installing Truenas Scale. The drives are in a zfs mirror configuration. All seems to be working well although there are many mysteries in the various settings and configuration choices available. I am beginning to think I should add another 8 tb drive and change the config to raid 5 or whatever the zfs equivalent is called. I understand that this will require off loading all the data and then restoring it from backups. What I don’t know is what other steps and/or processes are required. For example, do I need to start from scratch and reinstall Trusnas, or do I just delete the pool and create a new one, etc, etc. You can think of me as a total greenie who doesn’t understand much of the jargon and concepts involved.

So, can someone point me to (or provide) a simple set of instructions on how to do this after I have installed the third storage drive?

Much appreciated.
Thx

 

[morganL]

Just delete the pool and recrate a new pool with RAID level you want.

Export disconnect/delete....

Storage Dashboard

Provides information on the Storage Dashboard widgets and options for pools, devices, datasets, and disks listed on this screen.

www.truenas.com

 

[dwf2008]

Thank you!

 

[NugentS]

What model of WD Red are those?

 

[dwf2008]

8 tb
red plus

 

[ChrisRJ]

I am beginning to think I should add another 8 tb drive and change the config to raid 5 or whatever the zfs equivalent is called.

In general this is not recommended. But I am a big of starting with requirements/motivation/use-case: What makes you think into this direction? Without that knowledge it is not possible to give targeted guidance.

For a better understanding I strongly recommend the resources available on this forum. Please find a selection in my signature ("Recommended readings"). Also, be very careful with YouTube videos about TrueNAS. The vast majority is simply crap.

 

[dwf2008]

Now I am confused. I currently have 2 8 tb drives that are mirrored netting approx. 8 tb usable. By adding one more drive in a raid 5 or 6 , I would get 16 tb usable. What’s the downside of that?

 

[danb35]

What’s the downside of that?

Large disks in RAIDZ1 present what many consider to be an unacceptable risk of data loss. The resources Chris recommended to you explain this.

 

[Etorix]

Additionally, ZFS has no provision to change raidz# vdev geometry after creation. You can always replace drives in a vdev with larger drives to increase capacity. You can always add further vdevs to a pool to increase capacity and performance. You can always add or remove (danger!) drives in mirror vdevs, changing the redundancy level. You cannot (currently) widen a raidz# vdev: 3-wide at creation will remain 3-wide. You cannot change raidz level, e.g. from raidz1 to raidz2, the way Synology and others may allow to turn RAID5 into RAID6.

As you are aware of, any such change is through "backup-destroy-restore". Which means that ZFS wants you to "get geometry right first time".
A wish to change pool geometry suggests you have not thought hard enough about the right layout for your needs—and that now would be a good time to consider present and future requirements before proceeding to any change.

Oh, and you shall not use "raid 5" or "raid 6" when discussing your pool here.

 

[dwf2008]

Well . . . . as stated in my original post, I am totally new (and green) to this nas business and as such don’t even know what questions to ask. It seems the goal is to maximize storage capacity while taking advantage of the security features offered by the nas. So lets assume I have 3 8 tb drives and I am starting from scratch. What kind of configuration would you guys recommend? I was under the impression that a mirror setup requires an even number of drives.

 

[Etorix]

"Maximise storage capacity" and "security" are antagonists: More security = more redundancy = less usable space.

No NAS is "security" by itself: You need backups. And backups of the backups, off-line and off-site.

With that out the way, pool design on the NAS depends on your requirements. (You may have different pools for different needs.)
Block storage (iSCSI, zvols) demands mirrors (and using no more than 50% of the raw space).
File storage can use either mirrors or raidz. Raidz(2,3), with reasonably wide vdevs, is more space efficient—say, 6 to 8-wide raidz2: 67-75% space efficiency (of which you should use no more than about 80% of the raw space). But it comes at the cost of bringing in all drives from the start and of being poorly flexible (expansion means bring in another whole set of 6-8 drives).
By contrast mirrors are flexible: You can add—and even remove—vdevs as needed. You can also change the redundancy level, going from 2-way to 3-way (so, no, mirrors do not mean an even number of drives). Striped mirrors have higher performance than raidz. But this comes at the cost of poor space efficiency: At most 50% (same as 4-wide raidz2, which is arguably somewhat safer than a stripe of 2*2-way mirrors), dropping to 33% for 3-way mirrors.

Choose your poison!

The 'hidden' cost of using ZFS for your home NAS

 

[danb35]

I was under the impression that a mirror setup requires an even number of drives.

Not necessarily--you could go for a three-way mirror, but most people don't want to do that. Really, what we'd generally recommend is to get a fourth drive and then either have two mirrored pairs (more flexible, less redundant) or set up a four-disk RAIDZ2 pool (better redundancy here). RAIDZ1 can certainly be done, but there's a greater risk of data loss with that configuration. See:

Assessing the Potential for Data Loss

This guide was written to be read from top to bottom without jumps, with the intent of spreading awareness to both new and experienced users; the author of this document assumes the understanding of the concepts explained in the following...

www.truenas.com

 

[WI_Hedgehog]

Another question is what type of WD Red drives are those, SMR or CMR, because if it's SMR you might want to avoid fighting that dragon and use different drives (sourced on the cheap).

Really, someone should warn you that TrueNAS is Enterprise Level storage and requires Enterprise Level hardware which is not necessarily expensive, rather it is proven to be reliable. If you are using a PC as you mention (and not a Workstation grade machine) you're in for a rather abrupt lesson in "Stuff that worked Yesterday DOES NOT work Today," which happens at a random time somewhere around the Worst Possible Moment for things to go wrong. Ubuntu Server does a good job on PCs, see this post.

Please do not misunderstand me, TrueNAS is great--awesome even--and the people here (myself included) definitely want to help you succeed in building a NAS, however the goal is a bit more insightful of how to succeed for as little money/effort/time as required for your desired end use. As people are kindly trying to help you understand, TrueNAS has some Recommended Reading that saves lots of unnecessary trouble-shooting and scrapping of unusable hardware, plus money (the YouTube guys that are in it for the likes/subs leave that part out). ZFS isn't the "magic data savior"--it has a cost. And TrueNAS isn't installable on "just any old scrap machine destined for the dumpster," it's a bit more involved--worth it for what it does, but not quite that simple the first time someone uses it.

 

[dwf2008]

The drives are CMR.

 

[ChrisRJ]

Well . . . . as stated in my original post, I am totally new (and green) to this nas business and as such don’t even know what questions to ask.

And that was the exact reason why I pointed you to the readings; sorry if that wasn't clear.

Think of your situation a bit like having an appointment with a lawyer that you ask for help to draw up your last will. If you have no idea what your options are, all you can do is spend a lot of time to come up with many different ideas that are mostly shot down immediately, because they are not possible. (No offense, but it seems to me that is roughly where we are at the moment.)

Or you can tell the lawyer what you want to achieve and have him come up with suggestions. That still has the downside that the lawyer may misinterpret something you said. Or he has a bad day and forgets something. Or he is personally biased against one particular option because it is generally not great, but would be perfect you; only you missed to mention one little detail in your requirements that would have made that clear. Or .... You get the point.

To be able to ask good questions, a certain amount of knowledge about the solution realm is necessary. And I think it is also a matter of courtesy to the people who want to help. Because in contrast to the lawyer we don't get money. And that is fine. But for me there is a bit of an unwritten "contract" if I ask on a forum: Do your homework before you ask.

A bit long-winded, I know. And very much so because I was in the mood, not because of you .

 

[dwf2008]

Thank you Chris. Unfortunately, much of what I read in the “experienced” articles and documentation is so far over my head that I don’t really get much out of them. It would be much better if I had a “For Dummies” resource. The bottom line is I want to build/have a nas mostly for a learning experience and to keep my mind occupied while I deal with some serious and unpleasant health issues with my wife. I had this old but decent computer sitting around so I said to myself “why not”. So I bought a couple of big drives and got it running. I will use it mostly as a backup machine and may add plex server functionality in the future although I already have a dedicated plex machine.

The issue that prompted my initial post is that with the two 8tb drives in a mirror, my total capacity is just shy of 8tb and this is now almost half full. Hence I started thinking about expansion. I gather from the help received here on the forum that my best course of action would be to just add a third drive to the existing mirrored pool. Assuming that would give me about 12 tb usable, that would probably give me enough capacity for a long time. Do you agree this would be best?

 

[Etorix]

I gather from the help received here on the forum that my best course of action would be to just add a third drive to the existing mirrored pool. Assuming that would give me about 12 tb usable, that would probably give me enough capacity for a long time. Do you agree this would be best?

How are you arriving at 12 TB???
ZFS does not use "half the space" when using mirrors; it litterally "mirrors" (duplicate) the data over several drives. If you add the third drive to the existing vdev, you'll end up with a 3-way mirror vdev: Double redundancy, reasonably safe, but same 8 TB capacity.
If you were to add the third drive as a new (single drive) vdev, striped with the previous vdev, you'd end up with 16 TB of capacity but an unsafe setup: Failure of the single drive would take down the entire pool.

 

[Patrick M. Hausen]

The tldr; is: there is no good compromise in terms of capacity vs. resiliency to disk failure for a typical home user with 3 disks. The generally recommended minimal setup for a small NAS is 4 disks in a RAIDZ2.

 

[dwf2008]

How are you arriving at 12 TB???
ZFS does not use "half the space" when using mirrors; it litterally "mirrors" (duplicate) the data over several drives. If you add the third drive to the existing vdev, you'll end up with a 3-way mirror vdev: Double redundancy, reasonably safe, but same 8 TB capacity.
If you were to add the third drive as a new (single drive) vdev, striped with the previous vdev, you'd end up with 16 TB of capacity but an unsafe setup: Failure of the single drive would take down the entire pool.

Ok, thanks for the clarification.

 

[dwf2008]

The tldr; is: there is no good compromise in terms of capacity vs. resiliency to disk failure for a typical home user with 3 disks. The generally recommended minimal setup for a small NAS is 4 disks in a RAIDZ2.

What would be the capacity with that setup if the drives were 8 tb?