"Unlimited drives" is really only 30?

[shaunvis]

I kind of feel duped. I bought the Pro license because it says "Unlimited attached storage devices". The Basic and Pro clearly state the number of drives they support so I assumed unlimited meant unlimited. 

 

Now I'm finding out the limit is 28 & 2 parity drives. Is that really true or old info? If it's true, this is really a really deceptive way of selling the licenses. 

 

 

[Kilrah]

The Unraid array with its parity protection scheme supports 30 devices max.

You can use as many other drives as you want in pools, including with ZFS now.

[itimpi]

14 minutes ago, shaunvis said:

Now I'm finding out the limit is 28 & 2 parity drives. Is that really true or old info? If it's true, this is really a really deceptive way of selling the licenses. 

The limit is the number of drives physically attached to the server running Unraid - not the max in the main Unraid array.  
 

To be honest having only 2 parity drives protecting 28 data drives is getting a bit risky anyway.
 

You can have many pools in addition so the limit is then over 1000 drives or more (although whether a server could physically be made that could drive that many I have no idea.   We are also told that in a future release the current Unraid main array will become a pool type so you can then also have multiples of that.

 

we are expecting 

[shaunvis]

31 minutes ago, itimpi said:

The limit is the number of drives physically attached to the server running Unraid - not the max in the main Unraid array.  
 

To be honest having only 2 parity drives protecting 28 data drives is getting a bit risky anyway.
 

You can have many pools in addition so the limit is then over 1000 drives or more (although whether a server could physically be made that could drive that many I have no idea.   We are also told that in a future release the current Unraid main array will become a pool type so you can then also have multiples of that.

 

we are expecting 

 

I"m not sure what you mean by physically connected. Does that mean if I had a SAN or something like that I could use it? My plan was to add a netapp disk shelf (24 bays) to my server (12 bays). Would that not work when connected with a SAS cable but would via network?

 

[itimpi]

3 minutes ago, shaunvis said:

 

I"m not sure what you mean by physically connected. Does that mean if I had a SAN or something like that I could use it? My plan was to add a netapp disk shelf (24 bays) to my server (12 bays). Would that not work when connected with a SAS cable but would via network?

 

By connected I mean by something like SATA, SAS or USB.  
 

I do not think Unraid would have the drivers to handle a SAN, but if it did I suspect they would count as directly connected.

[Hoopster]

5 minutes ago, shaunvis said:

I"m not sure what you mean by physically connected

Phyically connected = connected to and detectable by Unraid at the time the server boots up.

 

For example, an external USB drive does not count if it is not connected to the server at server boot.  It can be connected after server boot as an unassigned device. This same USB drive does count in the 30 drive limit if it is connected to the server when the server is booted.

 

I don't know if/how Unraid would handle a SAN but if it can handle that, the SAN drives would most likely count against the limit.

[shaunvis]

So practically speaking, Unraid Pro is NOT "Unlimited attached storage devices" like it says when you go to buy the license then. Unless for some reason you wanted to plug in dozens of USB drives?

 

So they're just being deceptive and people like me that think they can just add a disk shelf or build a massive array can't actually do it

[JorgeB]

7 minutes ago, shaunvis said:

Unless for some reason you wanted to plug in dozens of USB drives?

They don't need to be USB, they can be any type of devices, as many as you can connect to the server, you can use 30 in the array, 1800 with pools, and unlimited number of unassigned devices.

[shaunvis]

11 minutes ago, JorgeB said:

They don't need to be USB, they can be any type of devices, as many as you can connect to the server, you can use 30 in the array, 1800 with pools, and unlimited number of unassigned devices.

So if I have 12 drives in my array and wanted to add a disk shelf with 36 (making 48 total) drives, how would I do that exactly?

 

 

[itimpi]

3 minutes ago, shaunvis said:

So if I have 12 drives in my array and wanted to add a disk shelf with 36 (making 48 total) drives, how would I do that exactly?

 

 

Up to you.    You can have up to 30 pools and each pool can have up to 60 devices.    As long as the disk shelf is connected (typically via SAS or SATA) to the server then the drives just show up as normal.

[shaunvis]

I guess I'm confused by pools then. All of my data is on the array. The only pool I have is my cache drive

 

So if I added a disk shelf, I'd basically set it up like I would my cache drives (pool) and then just use that for storage like I do my array disks?

 

If that's the case, what's the point of the array at all? Why not just have everything be a pool? I guess I don't know the pros/cons of one or the other

[JorgeB]

Depending on the use case pools can be better than the array, you can have for example a better performing zfs pool, I have servers where I only use the array, others have array and pools, and I have a couple of servers that only have pools.

[primeval_god]

4 hours ago, shaunvis said:

I guess I'm confused by pools then. All of my data is on the array. The only pool I have is my cache drive

 

So if I added a disk shelf, I'd basically set it up like I would my cache drives (pool) and then just use that for storage like I do my array disks?

 

If that's the case, what's the point of the array at all? Why not just have everything be a pool? I guess I don't know the pros/cons of one or the other

Pools can be single drive XFS, BTRFS raid, or ZFS raid. The "Array" is the only one that can be Limetech's proprietary unRAID storage (mix and match file systems and disk sizes  with up to 2 parity drives with max 30 total drives). The terms pool vs array and the fact that there must be an "Array" on an unRAID NAS are products of unRAID's slow evolution. From what I understand in a future version the term Array will go away and the unRAID storage type will become a type of pool and the requirement of always having an unRAID type array will be removed. As to whether or not multiple unRAID type pools will be supported that is likely even further in the future.

 

Also currently pools can be used to "cache" new incoming files that are then moved to the array (pools are an evolution of the older cache drive concept). In a future version the mover will support moving files between pools rather than only to and from the array.

Edited January 6 by primeval_god

[shaunvis]

1 hour ago, primeval_god said:

Pools can be single drive XFS, BTRFS raid, or ZFS raid. The "Array" is the only one that can be Limetech's proprietary unRAID storage (mix and match file systems and disk sizes  with up to 2 parity drives with max 30 total drives). The terms pool vs array and the fact that there must be an "Array" on an unRAID NAS are products of unRAID's slow evolution. From what I understand in a future version the term Array will go away and the unRAID storage type will become a type of pool and the requirement of always having an unRAID type array will be removed. As to whether or not multiple unRAID type pools will be supported that is likely even further in the future.

 

Also currently pools can be used to "cache" new incoming files that are then moved to the array (pools are an evolution of the older cache drive concept). In a future version the mover will support moving files between pools rather than only to and from the array.

Thanks, that helps. I have always just use Unraid "out of the box" and didn't know that much I guess.

 

That being said, I like the ability to match & match drives and upgrade them as needed. But you can't easily do that in a ZFS pool, correct?

[itimpi]

6 minutes ago, shaunvis said:

But you can't easily do that in a ZFS pool, correct

Yes.
 

That is why I think the proprietary Unraid array type will continual to be available even when it becomes ‘just another pool’ type.   At that point I expect multiple Unraid array type pools to be possible.

 

btrfs (the other file system type supported by Unraid) is easier to extend with additional drives than ZFS, but not as easy as the Unraid array type.

[primeval_god]

12 minutes ago, itimpi said:

That is why I think the proprietary Unraid array type will continual to be available even when it becomes ‘just another pool’ type.

It definitely will. No one has ever suggested that it wouldnt, as it continues to be the defining feature of unRAID.

 

13 minutes ago, itimpi said:

At that point I expect multiple Unraid array type pools to be possible.

 I believe they are working toward that, but i dont like to speculate on when Soon™ will be.

[ReinerSchweinlin]

Hi all,

 

this post seems to most closely match my question. I have been using trunas for quite a while but want to switch to unraid for the array feature.

 

One thing I can´t wrap my head around:

 

Suppose I have one parity disc and add a whole bunch of discs to it (30 it seems)... How on earth can one parity disc store the parity of for all the discs? I understand that if a disc starts to fail on a few sectors and one does a manual swap of this disc - the parity info of this one failing disc can be transfered to the parity drive - one has to wait - and then the defective disc is swapped...

 

But what happens if all of a sudden one disc dies completely in an instance. How could one parity drive store so much info for a lot of drives?

 

Or am I missing something obvious here ?

 

Thanx for helping me out with this probably stupid question...

[trurl]

Parity contains none of your data. Parity is just an extra bit that allows a missing bit to be calculated from all the other bits. Parity by itself can rebuild nothing. All bits of all other disks must be reliably read to reliably rebuild a disk.

 

This is basically the way parity works everywhere. Unraid just has its own implementation that allows each data disk to be accessed independently and so allows different sized disks in the parity array.

 

https://docs.unraid.net/unraid-os/manual/what-is-unraid/#parity-protected-array

[ReinerSchweinlin]

Thanx for getting back..

In another thread, I read about the unraid size calculator and someone mentioned, that a tool like this is unnecessary, since the actual available size simply is the size of all drives together....

From this comment, I deducted, that all drives - except the parity one - simply store the data without any redundancy between the data drives.

 

From your comment, I figure that this understanding is not correct ?

 

 

[trurl]

1 minute ago, ReinerSchweinlin said:

From this comment, I deducted, that all drives - except the parity one - simply store the data without any redundancy between the data drives.

 

From your comment, I figure that this understanding is not correct ?

That is correct. Not sure what you read in my comment that would make you think otherwise. Each data disk is an independent filesystem that can be read all by itself on any Linux. Parity disk contains parity bits, which is all of the redundancy needed to allow the contents of one disk to be calculated from the contents of all the other disks. Parity is not magic or even complicated. See the link I gave.

[ReinerSchweinlin]

Thanx. After reading your link thoroughly I now have a better picture of how it works and its clear now to me.

 

Since you mention that each disk could simply be read by any linux, one thought comes to mind: I assume the data is spread across the drives - or is it in a way that each file is living on one disk? Assuming, I would simply take one disc out of the array and put it in another machine, could I read the files completely of it? Or are the files scattered across all disks, so the chance of getting complete files tends towards zero ?

[primeval_god]

10 minutes ago, ReinerSchweinlin said:

or is it in a way that each file is living on one disk? 

This. Files do not span between disks.

[trurl]

User shares allow folders to span disks. Each file is contained completely on a single disk.

[ReinerSchweinlin]

Thank you  both for clearing this up This is great news Looking forward to getting my unraid installation up and running (just purchased a license..).