I'm considering using SSDs as array devices (not pool devices) in my Unraid setup and am curious about others' experiences with this. I know Unraid generally doesn't recommend SSDs for the array due to lack of TRIM support and potential performance degradation over time. But with advancements in modern SSD technology, I'm wondering if these issues still hold? 

 

1. Is performance degradation still a big issue with modern SSDs in Unraid arrays?

2. How have you found the stability and longevity of SSDs in the array?

3. Any specific configurations or SSD models that work better in this scenario?

 

@limetech Back in 2017 you mentioned:

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In a future release we do plan to add proper TRIM support to array disks.  Here's a heads-up on that.  In order to support TRIM in unRaid P or P+Q array, we must add code to the md/unraid driver and all SSD's in the array must support either "DX_TRIM" or "DZ_TRIM" mode as described above.  In addition there's a really good chance we will only support SSD's that support "DZ_TRIM" since to support "DX_TRIM" is a lot more work 

What is the update on this? 

 

36 minutes ago, Ice_Black said:

Is performance degradation still a big issue with modern SSDs in Unraid arrays?

It can be, modern SSDs can be worse than older ones, if you compare for example MLC with TLC or QLC models, especially for parity, since it will have to handle many more writes, having said that, if you use decent quality deveces like for example the 870 EVO, they should still maintain good performance.

 

Personally I would still recommend using a zfs pool instead, no issues with TRIM and much better performance, and with SSDs you can still IMHO get way with raidz1 for a decent size pool.

15 minutes ago, JorgeB said:

It can be, modern SSDs can be worse than older ones, if you compare for example MLC with TLC or QLC models, especially for parity, since it will have to handle many more writes, having said that, if you use decent quality deveces like for example the 870 EVO, they should still maintain good performance.

 

Personally I would still recommend using a zfs pool instead, no issues with TRIM and much better performance, and with SSDs you can still IMHO get way with raidz1 for a decent size pool.

 

Yea I am considering a ZFS pool, but one drawback is its limited extensibility, especially if you want to upgrade a single disk to a larger size. I think that’s what’s holding me back but still thinking about it.

 

For example, if you have a 3 x 4TB disk setup and want to add an extra disk in the future, you can’t simply expand the existing pool. You’d typically have to add a separate VDEV, which wouldn’t be part of the original VDEV’s redundancy. 

 

OpenZFS 2.3, currently available as release candidate, supports raidz expansion, I would expect that to be included with Unraid 7.1

you would need to find a way to make sure the SSD does not TRIM at all... Because if it does it will destroy your parity.. Not advised..

TRIM won't work on the array, it's not a problem for parity.