RAIDZ1 Updating capacity

[vl33l]

I will be (finally) fixing tomorrow an issue I do have with my USB boot key (have already a backup, just preparing things) and will add more space to my system.

I do have a RAIDZ1 volume :

Code:

[root@freenas ~]# zpool status																									 
  pool: MainVolume																												 
 state: ONLINE																													 
status: Some supported features are not enabled on the pool. The pool can														   
	   still be used, but some features are unavailable.																		   
action: Enable all features using 'zpool upgrade'. Once this is done,															   
	   the pool may no longer be accessible by software that does not support													 
	   the features. See zpool-features(7) for details.																			
  scan: scrub repaired 0 in 22h12m with 0 errors on Thu Feb  1 22:12:33 2018														
config:																															 
																																   
	   NAME											STATE	 READ WRITE CKSUM												 
	   MainVolume									  ONLINE	   0	 0	 0												 
		 raidz1-0									  ONLINE	   0	 0	 0												 
		   gptid/7bca072a-6c38-11e4-9f61-e03f4986cfc1  ONLINE	   0	 0	 0												 
		   gptid/7c97e50f-6c38-11e4-9f61-e03f4986cfc1  ONLINE	   0	 0	 0												 
		   gptid/8e8cc095-5e71-11e6-aac5-e03f4986cfc1  ONLINE	   0	 0	 0		

From what is shown on the documentation, the process is quite simple: shutdown the system, add the drives, go to the interface and add the drives from the volume manager.

I was planning to add two more disks, but from what it's shown on the documentation (http://doc.freenas.org/11/storage.html#extending-a-zfs-volume) I have a doubt that I would need to add an additional one, three instead of two:

• to extend a ZFS stripe, add one or more disks. Since there is no redundancy, disks do not have to be added in the same quantity as the existing stripe.
• to extend a ZFS mirror, add the same number of drives. The resulting striped mirror is a RAID 10. For example, if ten new drives are available, a mirror of two drives could be created initially, then extended by creating another mirror of two drives, and repeating three more times until all ten drives have been added.
• to extend a three drive RAIDZ1, add three additional drives. The result is a RAIDZ+0, similar to RAID 50 on a hardware controller.
• to extend a RAIDZ2 requires a minimum of four additional drives. The result is a RAIDZ2+0, similar to RAID 60 on a hardware controller.

Am I correct and I can only add three drives and not two?

Thanks!

 

[Chris Moore]

Yes. It is complicated. What are your hardware details?

Sent from my SAMSUNG-SGH-I537 using Tapatalk

 

[Chris Moore]

I went back and looked at your previous thread where you were fixing a boot drive problem. Your data drives are 6TB drives and setting those up as a RAIDz1 pool is kind of not a thing that would be suggested. If there were any way for you to backup your data elsewhere and reconfigure your pool to be a RAIDz2 pool instead, that would be a much better idea. I like six drives in a RAID-z2 for reliability reasons. Typically, any drive capacity over 1TB is considered to be too large to use with RAIDz1 because of the possibility that (especially as the drives age) a second drive failure could take the pool out before you can replace a failed drive. I have had two drives fail in one of my systems on the same day before, but those drives were almost 5 years old. It is just a bad feeling even when you are running RAIDz2, having two go out at once, but if you are running RAIDz1, it takes all your data.

 

[vl33l]

Well you're right, I could do a RAIDZ2 pool. The only issue is that I do have around 10TB of data, and quite hard to find space to backup it

my hardware is :

AMD A4-5300 APU with Radeon(tm) HD Graphics
16GB RAM
3x 6TB WD RED

I have to think of how or where I can backup my data temporarily. Any suggestions of a cheap service online maybe?

[Edit] When I want to increase the storage capacity, how many drives should I add when using RAIDz2?

 

[MrToddsFriends]

[Edit] When I want to increase the storage capacity, how many drives should I add when using RAIDz2?

Using six drives in total (after the upgrade) would be a good idea as Chris already stated, but having six drives is not necessary. Maybe reading this thread and using the ZFS Capacity Calculator suggested there would be a good starting point.

 

[vl33l]

Alright got it, no particular issues in just adding two drives then. I guess since I'm extending it data will not be erased right (I'm sure at 99% it's the case, but just want to be sure by experts ) ?

Well, on my NAS I only have movies and series, and very few personal documents (which I'm backing-up already on 2 locations: encrypted and stored in that form in the cloud, and on an external SSD - I did not automate this part but it's something I will do in the future, but not urgent as the documents are not changing that often). So I think I will stick with the RAIDz1.

 

[Chris Moore]

No you can't extend a RAID-z1 pool by just adding two drives. It doesn't work that way. I have seen people try and they end up with just a couple drives striped up next to the RAID-z1 part of the pool but those drives have no redundancy and if one of them fails, the pool fails.
You would need to destroy the pool and make a whole new set or add another vdev which would take 3 drives in another RAID-z1 vdev.

 

[Chris Moore]

I'm sure at 99% it's the case, but just want to be sure by experts

You are not understanding.

Please look at this resource on how ZFS works:
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

 

[vl33l]

Ok. How I'm supposed to work around that? I have seen the minimal requirements that says 3 disks minimal, but wasn't aware of the fact I can't just add two more drives.

Do I need to follow any specific procedure? I didn't found an answer to that on the web :/

Thanks

 

[vl33l]

You are not understanding.

Please look at this resource on how ZFS works:
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

will check that, didnt saw this prior replying !

 

[vl33l]

Alright thanks for pointing me to this presentation, I definitively had to read that to understand what you were saying and what huge mistake I was going to do!! I did backup it on my notes, just in case we never know :) (btw, the last update is from March 2016 for FreeNAS 9.10, any idea an update has been made to this presentation since? It really has a lot of useful information on it, worth reading it!!)

So if I understood correctly, it's better to get a third disk (typically of another brand such as WD) and create another vdev which will be of the same size of the one I do currently have right? However in terms of storage, will it be completely transparent and just add more space to the zpool? I'm guessing yes, but want to be sure.

I will now have to think about how I do backup my important data into my SSD, but this will be another topic :)

 

[Chris Moore]

it's better to get a third disk (typically of another brand such as WD) and create another vdev which will be of the same size of the one I do currently have right? However in terms of storage, will it be completely transparent and just add more space to the zpool? I'm guessing yes, but want to be sure.

Yes. I think you are getting it now.

 

[vl33l]

Can it be done by using the Volume Manager http://doc.freenas.org/11/storage.html?highlight=vdev#volume-manager ?

[Edit] I think I just got it: http://doc.freenas.org/11/storage.html?highlight=vdev#extending-a-zfs-volume should be the correct way of doing it I believe?

 

[Chris Moore]

Can it be done by using the Volume Manager http://doc.freenas.org/11/storage.html?highlight=vdev#volume-manager ?

[Edit] I think I just got it: http://doc.freenas.org/11/storage.html?highlight=vdev#extending-a-zfs-volume should be the correct way of doing it I believe?

Yes, that is the spot. Just be careful of what you do here because it will let you do things that you should not do.

 

[vl33l]

Alright, by end of the month I will be getting the third disk, so I may post here for some additional help if I'm confused with something.

Again thanks a lot, definitively learned something! ;-)

 

[ethereal]

You could run FreeNAS in something like virtualbox to play around and practice safely before you try it for real.

 

[wblock]

Yes, and drives attached to the FreeNAS VM can be disk files so as to not fill up the host machine. For testing, they do not need to be very big. I use 10GB as an arbitrary size, which is big enough to hold a little data. Since they are sparse files on the host, they don't actually occupy that much space unless filled.