So i have an SSD that keeps vanishing from unraid... 

This is one of 2 identical Kingston 120GB ssd's that i have configured as a btrfs cache pool. These are both connected to a cross flashed IBM ServeRAID M1015 card. (they are the only 2 drives currently connected to that card)

That cache pool had never had a problem until a couple months ago when after rebooting the box one of the drives randomly became unassigned. I could not figure out what happened so i just re assigned the drive and started the array. That wiped the drive but its a redundant pool and there wasn't anything important on it at the time anyway. Since then the array has been running continuously and has not had a single issue with that drive.

 

Then yesterday i started messing with some unrelated network issues that required me to take the array offline several times.

This is where i started running into issues again. On several occasions the instant i took the array offline the drive would just vanish 

 

I found that there are a number of ways i can get it to come back. Sometimes it would just come on its own without me doing anything. I would just refresh the page and it would be there (I suspect thats what happened when it "unassigned" itself a couple months ago) 

Other times i would need to reboot at least once but sometimes several times before it would show up again. And i also found that simply plugging the drive and plugging it back in again would also almost always fix it. I tried using different connector on the SAS breakout cable but that made no difference.

Also sometimes the drive would show up like this. 

(It did not assign itself like that i did so i could take the screen shot)

 

I find this rather confusing... It sounds like a bad ssd but if that was the case why would it only ever show problems when i stop the array? Im sure i could start the array rite now and as long as i dont ever stop it im sure it will still be running fine in 6 months.

The other possibility is my cross flashed LSI card but i suspect that would effect both drives, There is also the ebay SAS breakout cable to consider but the other drive is connected to the same cable and i tried all 3 remaining plugs on that cable. They all have the same issue. The power connection is also a little sketchy but i dont think this is an issue with any physical connections because last i checked electrical faults dont wait for you to press "stop array" 

Connect that SSD to one of the onboard SATA ports, swap with a disk if needed, use a new/different power cable, and if the same keeps happening it's likely the SSD.

 

P.S. you should the onboard SATA for the SSDs anyway, to have trim support.

Ok so looks like your rite its the power connection. I swapped the sata cable with another drive and nothing happened. So then i swapped the power cables and suddenly the drive i swapped the cables with was not detected. It makes sense i ran out of sata power plugs on my psu so i hacked in some additional plugs from a cheap molex to sata converter (very cheap apparently) This answer just didnt make much sense because the issue only occurs when the array is offline... Unless i am wrong in assuming unraid will throw all sorts of errors at me if a cache drive is lost while the array is online?

Oh... Ok... so it does give "an error" but its just a notification... I dont pay much attention to those because i get a lot of them for system status and what not. (i may want to adjust my notification settings)

I kinda expected the drive to go red and display some "device missing" message or something. Instead other than that notification it just pretends nothing is wrong...

5 hours ago, brandon3055 said:

I kinda expected the drive to go red and display some "device missing" message or something. Instead other than that notification it just pretends nothing is wrong...

See here on how to better monitor the pool:

https://forums.unraid.net/topic/46802-faq-for-unraid-v6/?do=findComment&comment=700582