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joshbgosh10592

Separate SSD Array

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I'm running unRAID 6.7.2 pro version with a 10TB Parity, with 2x10TB, 1x2TB, soon to add 2x2TB, 1x3TB, and 1x4TB as data drives. These are all spinning disks.

I'd like to however also add an array for 1TB SSDs to house VMs for a Proxmox cluster. I can't add these to the normal pool because the parity drive would slow everything down.

I'm tossing the idea of having a hardware RAID 5 and present that to unRAID's Unassigned Devices as a single virtual drive, but then I can't see if there's a failure (these would be internal drives).

Is there a way to make this a software controlled RAID 5 so unRAID can alert me of any failures, but keep these drives separate from the spinning disks?

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You can run an unassigned cache pool but I can't remember if btrfs supports RAID5 or not. Jonnie may know, he's the expert in btrfs stuff here.

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23 minutes ago, joshbgosh10592 said:

I'm running unRAID 6.7.2 pro version with a 10TB Parity, with 2x10TB, 1x2TB, soon to add 2x2TB, 1x3TB, and 1x4TB as data drives. These are all spinning disks.

I'd like to however also add an array for 1TB SSDs to house VMs for a Proxmox cluster. I can't add these to the normal pool because the parity drive would slow everything down.

I'm tossing the idea of having a hardware RAID 5 and present that to unRAID's Unassigned Devices as a single virtual drive, but then I can't see if there's a failure (these would be internal drives).

Is there a way to make this a software controlled RAID 5 so unRAID can alert me of any failures, but keep these drives separate from the spinning disks?

 

I do exactly this with SSDs outside the array in a BTRFS RAID5 config

Very easy to set up

 

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=462135

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On 8/12/2019 at 3:30 PM, therapist said:

 

I do exactly this with SSDs outside the array in a BTRFS RAID5 config

Very easy to set up

 

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=462135

Thank you! That seems easy enough. I was hoping for a GUI way (feels less hacky that way lol), but I'm not afraid on a Linux command line.

 

Now to figure out how to power the additional drives.. I'm using the SuperMicro 12 drive chassis with my 2 drive cache pool using command strip velcro to the side of the case powered off one molex to 2 sata adapter. Not sure if it's safe to run 5 SSDs off a single molex plug lol..

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8 hours ago, joshbgosh10592 said:

Not sure if it's safe to run 5 SSDs off a single molex plug

Depends on the connectors used. The source isn't the issue, a standard 4 pin connection can handle the current just fine. It's the SATA end of the power adapter that can cause fires. https://www.crucial.com/usa/en/dangerous-molex-to-sata-cables

That link does a poor job of demonstrating which types of adapters to avoid, suffice it to say that some adapters are much safer than others. Do your research.

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On 8/12/2019 at 3:30 PM, therapist said:

 

I do exactly this with SSDs outside the array in a BTRFS RAID5 config

Very easy to set up

 

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=462135

Thank you! It seem easy enough, however when I'm trying to do this, the

btrfs dev add -f /dev/sdg1 /mnt/disks/nas-ssd-pool

fails with: "ERROR: /dev/sdg1 is mounted" which makes sense, because the directions said to mount it, but it also makes sense that the command cannot change the config of a file system while it's mounted.

Any idea on this one?

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On 8/14/2019 at 7:28 PM, jonathanm said:

That link does a poor job of demonstrating which types of adapters to avoid, suffice it to say that some adapters are much safer than others. Do your research.

Have a look at this YouTube video for the type of SATA connectors to you should be looking for:

 

  

 

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8 hours ago, joshbgosh10592 said:

fails with: "ERROR: /dev/sdg1 is mounted" which makes sense, because the directions said to mount it,

No, you mount the first device than add additional devices, the additional devices can't be mounted.

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6 hours ago, johnnie.black said:

No, you mount the first device than add additional devices, the additional devices can't be mounted.

Right, I mounted only the first device with "nas-ssd-pool" as the mount name. When I mount it via UD's UI, /mnt/disks/nas-ssd-pool is there, but when it's unmounted, it vanished (which is what I'd expect).

I don't try to mount the other devices.

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I don't try to mount the other devices.

 

"ERROR: /dev/sdg1 is mounted"

This implies devices sdg is mounted, and this should be an additional device, not the original device mounted in /mnt/disks/nas-ssd-pool

 

 

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2 minutes ago, johnnie.black said:

 

 

This implies devices sdg is mounted, and this should be an additional device, not the original device mounted in /mnt/disks/nas-ssd-pool

 

 

I was actually just editing the quoted post, sorry about that.

I think I got it! Thank you!!

Now my next and hopefully final question..

Shouldn't System and Metadata say RAID5? The UI shows the sdg as having 3TB free, when it should have only 2.

Here's what I ran, and the results of btrfs filesystemdf:

root@NAS:~# btrfs balance start -dconvert=raid5 -mconvert=raid1 /mnt/disks/nas-ssd-pool/
Done, had to relocate 4 out of 4 chunks
root@NAS:~# btrfs filesystem df /mnt/disks/nas-ssd-pool/
Data, RAID5: total=2.00GiB, used=1.00MiB
System, RAID1: total=32.00MiB, used=16.00KiB
Metadata, RAID1: total=1.00GiB, used=112.00KiB
GlobalReserve, single: total=16.00MiB, used=0.00B

 

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Posted (edited)
7 minutes ago, joshbgosh10592 said:

Shouldn't System and Metadata say RAID5?

It's safer to keep the metadata raid1.

 

The GUI won't report the correct free size since it doesn't account for parity, but at least when used with UD the free space will be recalculated based on the used space, so it's closer to correct as the pool gets filled up, but if you want to know the real free space just subtract the space needed for parity, so if you have a 3 1TB device raid5 pool:

 

GUI shows 3TB free - real free space is 2TB

GUI shows 1.5TB free - real free space is 1TB

GUI shows 450GB free - real free space is 300GB

etc

 

Used space will always be correct on the GUI.

Edited by johnnie.black

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1 minute ago, johnnie.black said:

It's safer to keep the metadata raid1.

True, I thought it would show raid5 for the system (I set mconvert to raid1, so I was expecting that to show raid1).

2 minutes ago, johnnie.black said:

The GUI won't report the correct free size since it doesn't account for parity, but at least when used with UD the free space will be recalculated based on the used space, so it's closer to correct as the pool gets filled up, but if you want to know the real free space just subtract the space needed for parity, so if you have a 3 1TB device raid5 pool:

 

GUI shows 3TB free - real free space is 2TB

GUI shows 1.5TB free - real free space is 1TB

GUI shows 450GB free - real free space is 300GB

etc

 

Used space will always be correct on the GUI.

Thank you! Is there a calculation for that? I was expecting it to be "Free space, minus 1TB"

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1 minute ago, joshbgosh10592 said:

Is there a calculation for that?

You need to subtract the parity size, with 3 devices correct free space is 2/3 of displayed free size, with 4 devices is 3/4, etc.

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