Register for the iXsystems Community to get an ad-free experience and exclusive discounts in our eBay Store.

Slideshow explaining VDev, zpool, ZIL and L2ARC for noobs!

Ericloewe

Not-very-passive-but-aggressive
Moderator
Joined
Feb 15, 2014
Messages
16,025
Thanks
3,880
No, I didn't move this to the Resources section because of the missing file(s). I was hoping to either have the time to write up a new, shorter version or that someone would beat me to it.
So far, neither has happened.

If you want to submit your own version, just submit a Resource in the Resources section. If you have any questions or would like a review before submitting, PM me.
 
Joined
Mar 14, 2018
Messages
43
Thanks
4
Great slide-show, found it very informative!
 
Joined
Nov 11, 2016
Messages
32
Thanks
1
Thank you for all your work. The slideshow and this thread are very informative.

That said, here are some things you might consider for future revisions, bearing in mind the audience of noobs (and the fact that in regard to FreeNAS, I belong to this category):
  1. Break the presentation into smaller parts. Clearly a single presentation on physical drives, VDevs, and zpools is enough to chew on for a first bite. And this part of the slide show doesn't even begin to touch on file systems, shares, or zvols. Zils and L2ARC seem to have more to with optimizing performance on larger systems and might easily be moved to a separate presentation. Other useful information -- NICs, ECC memory, etc. -- also deserves to be a separate topic.
  2. For any and all of the above, it would be helpful to include screenshots of the GUI, showing how to do things like create a VDev or combine them into a zpool. Perhaps links to specific pages in the manual would be sufficient.
  3. It would also be helpful to have a few examples/case studies/recommended configurations for different uses a noob is likely to want (e.g., media server, shared backup device, etc.)
  4. I realize how important it is to RTFM, but many people need to augment such learning with learning by doing. This is especially true for people who are starting out. They need reinforcement and a chance to make some mistakes before they grasp some things that need to be mastered and then built upon. This implies perhaps thinking more in terms of a tutorial than a lecture (presentation). It would be especially helpful to target at least three different audiences -- (1) people contemplating building their own FreeNAS server, (2) those who have built one and are now in the process of setting it up, and (3) those who have one and (a) want to modify it by adding drives or changing its configuration or (b) have to troubleshoot a problem. For example, I find myself in the second category, and it would be really helpful to be able to try some things before diving in and configuring what will become my production system; but after viewing the presentation I am scared to death of playing around with anything related to disk configuration because the presentation emphasizes how irreversible such decisions are and how interdependent data are on the overall configuration. So it would be great if there were some way to try some things, erase them, and then implement the final configuration.
  5. Breaking the presentation up would also be advantageous for this forum thread, which is now 15 pages long but quite wide-ranging, and it might make maintaining the presentation(s) easier because some things, like the logical relationships within data storage, are likely to change with new versions of FreeNAS, while other things, like good hardware practices, are more likely to be the same from version to version. For example, suppose one had to add slides about a new way to combine VDevs, then all references to these added slides would have to change. OTOH, if there were a separate presentation for, say, performance optimization, its references would not change.
These are only suggestions, but my intent is that they would make an already excellent learning tool even better.

Thanks.
 
Last edited:

Ericloewe

Not-very-passive-but-aggressive
Moderator
Joined
Feb 15, 2014
Messages
16,025
Thanks
3,880
I'm actually working on a newer version of this (slowly, time is limited), since Cyberjock's version is getting old. Thanks for the feedback!

but after viewing the presentation I am scared to death of playing around with anything related to disk configuration because the presentation emphasizes how irreversible such decisions are
I mean, if you're still setting things up, just play around and destroy the pool as often as necessary.
 
Joined
Nov 11, 2016
Messages
32
Thanks
1
I'm actually working on a newer version of this (slowly, time is limited), since Cyberjock's version is getting old. Thanks for the feedback!


I mean, if you're still setting things up, just play around and destroy the pool as often as necessary.
Thanks. IIRC, from viewing the slide show I didn't know you could do that.
 

Chris Moore

Super Moderator
Moderator
Joined
May 2, 2015
Messages
9,355
Thanks
2,991
If you don't have data on it yet, or if the data is just a copy for testing, you can do whatever you want.

Sent from my SAMSUNG-SGH-I537 using Tapatalk
 
Joined
Apr 8, 2018
Messages
31
Thanks
3
The guide is really useful - thanks very much! I thought I'd add my tuppence worth if you are working on something new:
  1. I'd love to see a ppt version back with animations too
  2. I agree with @Monkey_Demon that breaking it into a couple of separate files / topics / parts might be good too.
  3. I think some screenshots of a running system pointing out what a physical drive, VDev, Pool, Zpool, etc look like in the interface would be really helpful.
  4. I found there is some inconsistent terminology across the various areas (the user guide, the interface, and the presentation). It might be worth having a table somewhere like a rosetta stone that clears up what each item is called in the separate areas. For example, in the guide at volumes,
I'd like to help if I can, but I am still defintel a noob and haven't got loads of spare time, but feel free to contact me and I will try and help with the presentation if I can!
 
Joined
Aug 6, 2018
Messages
5
Thanks
0
Slideshow explaining VDev, zpool, ZIL and L2ARC and other newbie mistakes!

I've put together a Powerpoint presentation(and PDF) that gives some useful info for newbies to FreeNAS. I decided to create this slideshow because in the last 5 months I've been on this forum I've seen a lot of people confused about vdevs, zpools, zils, l2arcs, etc. Hopefully we can put to rest a lot of the confusion once and for all.

We get a large amount of duplicate threads with the same questions being asked every other day. Personally, we get them so often I decided to stop answering them and decided a better use of my time would be to create this presentation. I literally read every thread and every post that goes on the forum. So if I don't answer either the answer is in the thread or the answer is found in this presentation or FreeNAS manual. Answering every 3rd thread with "Consult the manual" gets a little old after a while and I have better uses for my time.

This presentation also contains a lot of information that is explained in a little more detail for new users. It includes many common errors newbies make and can save you some heartache. If you are brand new to FreeBSD, I recommend reading the manual cover to cover. There are a lot of recommendations throughout the manual, and they are typically there because they are an error trap for many people.

I've saved this in Powerpoint because I have some animations in the slideshow. I'm not sure what other formats would work. If you would like this in another format that supports animations please let me know and I'll see what I can do. Currently I provide this in a powerpoint presentation and PDF. The PDF has no animations therefore the Powerpoint is preferred.

I'll try to keep it updated as necessary. If this presentation helps you please "like" it so others can see that it really is worth the time to read!

Updated as of: May 2, 2016

Powerpoint: https://dl.dropboxusercontent.com/u/57989017/9.10/FreeNAS Guide 9.10.pptx.zip (This is the preferred format because it includes animations)

This version is currently unavailable.

PDF via Google Docs: https://drive.google.com/file/d/0BzHapVfrocfwblFvMVdvQ2ZqTGM/view?usp=sharing

PDF: https://dl.dropboxusercontent.com/u/57989017/9.10/FreeNAS Guide 9.10.pdf.zip
**********This link is dead*****************
 

Chris Moore

Super Moderator
Moderator
Joined
May 2, 2015
Messages
9,355
Thanks
2,991

danb35

FreeNAS Wizard
Joined
Aug 16, 2011
Messages
10,318
Thanks
3,664

danb35

FreeNAS Wizard
Joined
Aug 16, 2011
Messages
10,318
Thanks
3,664

rmccullough

FreeNAS Experienced
Joined
May 17, 2018
Messages
143
Thanks
15
@cyberjock, thank you for the guide. I do have a couple of questions.

The guide says "Once you add a VDev to a zpool it cannot be removed for any reason." This sounds like an "absolute" statement, and I want to make sure it is absolutely true. Can you "remove" the VDev from a zpool by starting over? Like if I take the disks that make up the VDev and format them. I understand this will cause me to lose all data in the zpool, but would this be a way to "remove" a VDev from a zpool?

Also, the guide says "You cannot add more hard drives to a VDev once it is created." What if a drive fails? Can I replace it? Should this be clarified in the guide (it mentions this a couple times) to say that you cannot increase the total # of drives in the VDev once it is created (but you can replace them, such as in the case that one fails)?

I don't mean to be splitting hairs, but I want to make sure I truly understand what is being said.
 

rmccullough

FreeNAS Experienced
Joined
May 17, 2018
Messages
143
Thanks
15
Related to adding a drive to a VDev, if I have a disk that will be a "hot spare", does it get added to the VDev when it is created? Or is there a process for designating it as the spare after configuring the VDev?
 
Joined
Sep 13, 2014
Messages
103
Thanks
25
The guide says "Once you add a VDev to a zpool it cannot be removed for any reason." This sounds like an "absolute" statement, and I want to make sure it is absolutely true. Can you "remove" the VDev from a zpool by starting over? Like if I take the disks that make up the VDev and format them. I understand this will cause me to lose all data in the zpool, but would this be a way to "remove" a VDev from a zpool?
It's as simple as removing a vdev, or a vdev failing on it's own, destroys the zpool. If you don't care about losing everything on the entire zpool, then you can remove, reformat and change the disks any way you like.

Also, the guide says "You cannot add more hard drives to a VDev once it is created." What if a drive fails? Can I replace it? Should this be clarified in the guide (it mentions this a couple times) to say that you cannot increase the total # of drives in the VDev once it is created (but you can replace them, such as in the case that one fails)?

I don't mean to be splitting hairs, but I want to make sure I truly understand what is being said.
I think you're arguing semantics.

Perhaps I'm putting 2 and 2 together and coming up with 5 but you sound like a bit of a worrier... second guessing what you're almost sure is the correct answer. I don't say that in a bad as I'm a worrier too. When there's a subject I don't feel confident in my understanding of, such as when I first started out with FreeNAS, I tend to second guess everything and want answers with no room at all for doubt... especially when it relates to the safety of my data.

This is a good example of such a case. You could argue that replacing a disk requires adding a disk to the system but that's approaching the question in a backward way. If one of the legs on the chair your sitting on were to snap and you were to remove it and replace it with a new leg, you're not adding to the number of legs your chair has. It started with four, one snapped and was removed leaving three legs, now you've added the replacement leg, you still have four legs.
 
Last edited:
Joined
Sep 13, 2014
Messages
103
Thanks
25
Related to adding a drive to a VDev, if I have a disk that will be a "hot spare", does it get added to the VDev when it is created? Or is there a process for designating it as the spare after configuring the VDev?
Here's a link to the relevant section of the manual. http://doc.freenas.org/11/storage.html#hot-spares

The relevant line for you being "Hot spares can be added to a volume during or after creation".
 

danb35

FreeNAS Wizard
Joined
Aug 16, 2011
Messages
10,318
Thanks
3,664
Can you "remove" the VDev from a zpool by starting over? Like if I take the disks that make up the VDev and format them.
Well, yes, but then you don't have a pool any more.
What if a drive fails? Can I replace it?
Of course. Replacing is not adding.
if I have a disk that will be a "hot spare", does it get added to the VDev when it is created?
A hot spare belongs to the pool, not to any vdev in the pool. You can designate it at the time the pool is created or afterward.
 
Top