I think I remember seeing somewhere that the trim plugin, and scheduling trim is no longer necessary or recommended after upgrading to 6.9. I am not sure if I actually read this, or not. Hoping someone could verify this info for me. 

It's not necessary for btrfs pools, still is if you use XFS.

1 minute ago, JorgeB said:

It's not necessary for btrfs pools, still is if you use XFS.

 

That is the fastest response I have ever gotten. Has the recommendation changed on what filesystem to use for cache/pool drives? I was always told btrfs only for multiple drives, otherwise XFS due to stability.

XFS is the best choice for most users using single device cache, unless you need the btrfs features.

3 minutes ago, JorgeB said:

XFS is the best choice for most users using single device cache, unless you need the btrfs features.

 

Thank you sir. It occurs to me that I had read before that the primary hang up with using SSD's in the array was something to do with the way it handled trim. Is this possibly foreshadowing for this feature being made more possible in the near future?

Array devices still can't be trimmed, possibly in the future.

Not only is the TRIM utility not useful for btrfs formatted SSDs (because TRIM is built in to btrfs) but it appears to be positively dangerous. My recently destroyed btrfs SSD cache drive was using the UnRAID TRIM utility (on advice from other UnRAID users)  and succumbed after a couple of months, turning read-only with the error:

 

cache and super generation don't match, space cache will be invalidated

 

If I'm reading this aright (always a big IF) and the current UnRAID implementation of TRIM is destructive on btrfs-formatted SSDs, shouldn't the utility be updated to detect btrfs, warn the user, and render itself inactive?

 

The good news is that only the btrfs formatting was destroyed. Reformatted as xfs, the SSD lives on. But if I can get confirmation of my assertions here, I'm inclined to return the SSD to btrfs.

 

-- 

Chris

Edited May 25, 20215 yr by bidmead
spelling correction

1 minute ago, bidmead said:

Not only is the TRIM utility not useful for btrfs formatted SSDs (because TRIM is built in to btrfs) but it appears to be positively dangerous.

It's perfectly fine to run trim on btrfs filesystems.

 

1 minute ago, bidmead said:

cache and super generation don't match, space cache will be invalidated

This is just a warning, unrelated to trim, and not a reason to make a filesystem read-only, something else must have happened.

Thanks for that, @JorgeB

 

This was the other error being thrown up. Can we be sure it wasn't the result of a TRIM conflict?

 

-- 

Chris

 

 

That is a serious error, but unlikely to be the result of trim, unless the device has a buggy firmware.

I've raised a query with the vendor about this, @JorgeB. I'm continuing to run the cache xfs-formatted with a weekly TRIM. I'll report back here if I find out more.

 

-- 

Chris

Edited May 26, 20215 yr by bidmead
s/monthly/weekly

8 minutes ago, bidmead said:

I've raised a query with the vendor

 

What's the device in question? Other people might have them too so would be useful to know, in case it does have buggy firmware.

Good question, @John_M. It's all set out in the UnRAID story. The SSD in question uses RAISE and I did ask the forum earlier whether this made an external TRIM utility redundant but the response seemed to be to go ahead with TRIM anyway.

 

I still have my doubts about whether the combination of btrfs, TRIM and RAISE may not be asking for trouble. I understand that OWC, the manufacturer, is currently investigating this. Meanwhile, I'm running the SSD, now happily formatted as xfs. TRIMmed weekly, uneventfully.

 

-- 

Chris

Edited May 31, 20215 yr by bidmead
adding links

On 5/8/2021 at 5:41 AM, JorgeB said:

It's not necessary for btrfs pools, still is if you use XFS.

 

THANK YOU!!!!

I just removed my TRIM cron.

 

Wish all a great week.

 

Lucas

 

 

I was just wondering the same thing since I just upgraded my 1TB HDD cache to 2*500-SSD raid1

On 5/8/2021 at 2:46 AM, JorgeB said:

XFS is the best choice for most users using single device cache, unless you need the btrfs features.

 

I have one XFS cache SSD. If I want to add another, I should go back to btrfs?

If you add another pool (a cache pool, and say a downloads pool), then XFS is still the way to go.  BTRFS is really only used if you have a multi-device pool (2 SSDs for redundancy in a pool named "cache")

Redundancy was the plan... I'm refreshing my server, so maybe I'll see how it handles without cache. Is this topic documented anywhere? Is it as simple as adding a second btrfs SSD, moving files over, then switching the current SSD to btrfs and adding it back?

https://wiki.unraid.net/Manual/Storage_Management#Switching_the_pool_to_multi-device_mode