Can you combine SSD and HDD disk into one SHR storage pool

[BobW]

Hi,
Question is it possible to combine 1 SSD disk and 2 HDD disk into one SHR storage pool with one volume?
At the moment I have 1x 2TB SSD into storage pool 1 (volume 1)
And 2x 8TB HDD into storage pool 2 (volume 2)

On the SSD I have all the applications / Docker/ MailPlus-server and also the video folder
On volume 2 I have Homes / music / photos and some other shared folders.

My thought was that it couldn’t be combined that why I chose the way, but of course I realize that volume 1 doesn’t have raid protection.

 

[Rusty]

I would highly advise against it. Having different speed drives is already not advised, let alone with different technology and mechanism. Leave it as it is. Considering those are 3 drives in total you obviously have a 4bay or larger NAS. So just add one more SSD in time into volume1 and make it redundant.

 

[EAZ1964]

I think it is possible, technically there is no reason it should not work.
Obviously you lose the access time benefits of the SSD for your aps and docker.
Take care: you cannot add the 2TB to the 8TB pool, the reverse is possible.

Make the decision on what is most important: access times for the apps, dB, and docker, or redundancy.
If internal NAS speeds are important (with docker, web/php, mailplus etc it for sure is) keep the SSD separate and think about adding another ssd for redundancy. If budget is a constraint, consider a 1TB if you move the Videos away from the SSD, typically there is no benefit of having the video's on ssd.

 

[BobW]

@Rusty and @EAZ1964 thanks for your advice!
My choice was indeed based on speed for the SSD for Docker, VMM etc.
but after some reading and such, it got me thinking and I thought I had made a mistake with this configuration.
That is why I asked my question here anyway.
Fortunately, you guys were able to convince me that I made a good choice;-)

In the long run, I may add a 2nd SSD for redundancy.
I currently have the SSD in bay 1 and the 2x 8TB in Bay 2 and 3, this means the 2nd SSD would be in Bay 4 is that a problem?

 

[jeyare]

just my 2 cents:
- Rule No.1 - never mix different Vendor disks within the RAID (e.g. WD + Seagate)
- Rule No.2 - never mix different models from the same vendor within the RAID (diff geometry, diff cache, ...) ... (e.g. Blue + Black)
- Rule No.3 - never mix a different kind of technologies SSD (QLC with TLC, ...), or HDD (CRM, SRM, ...), even mix of all of them

Otherwise, you will get:
- an unstable environment in case of mixed firmware cache for write - you can get write hole events = data lost
- I can continue till the end of the next day ...
Simple - it is a bad idea.

 

[EAZ1964]

just my 2 cents:
- Rule No.1 - never mix different Vendor disks within the RAID (e.g. WD + Seagate)
- Rule No.2 - never mix different models from the same vendor within the RAID (diff geometry, diff cache, ...) ... (e.g. Blue + Black)

As always, there are different opinions on the above.
I have always mixed the disks (diff age, verdor and/or model) on purpose to decrease the risk that the disk fail at the same time, and lower the risk that a second disk dies when rebuilding the first one (have plenty of use cases for this).
Modern RAID is robust and should not fail for this reasons. Having said that, I would not mix disks with different RPM.