Hello,
I have 2 drives in mirror for proxmox backup and nfs.
I have setup like this:
Disk Type: HDD
Description:
Model: ST1000DM003-1SB102
Transfer Mode: Auto
Rotation Rate (RPM): 7200
HDD Standby: 60
Adv. Power Management: 1
Enable S.M.A.R.T.: No
S.M.A.R.T. extra options:
And one drive go to spindown mode like in 5 seconds after inactivity. How can i stop from immediate spindown?
This is an SMR drive, not suitable for ZFS. They tend to spin down as an archive drive.
If you need to know about CMR vs SMR
SMR vs CMR ServeTheHome
I had this setup for like month and this starts happening today.
Not sure if you are saying that this was not happening for the past month or if you are saying that you just noticed it. While I will not say that you cannot make an SMR drive not sleep, it has been my experience for the SMR drives I’ve been exposed to, they all sleep regardless of the SMART commands given. The only way to keep it awake is to write or read data.
If you feel the drive previously didn’t sleep, It could be that you wrote a lot of data and you never heard the drive spin-down because it was reorganizing the data which takes a lot of time, which is why SMR drives are not good on a ZFS system.
im 100% sure i start happening now bc i monitor truenas server with smart plug. Drive normally slept after set period of time. Now it start ignoring it.
I guess all I can say is: What changed from the time it was working as you desired to when it started to sleep? If the answer is nothing, then I would say you didn’t notice the drive sleeping, but if you made some changes, that could be the difference.
You have some investigating to do. Hopefully you find a satisfactory answer.
Try setting this to a higher value (at least 128) to avoid that the disk spins down due to the advanced power management settings. With a setting of 1, you have maximum power savings with spindown. Many drives I know spin down very quickly with this setting.
So, if you read you correctly, you’re saying that TrueNAS used to be able to allow the drives to sleep for longer earlier, but not anymore - something is waking them up?
The OP said that one drive spins down too quickly and he wants to keep it running longer, like it use to.
Are you sure? This is an old model, the product sheet I found was from 2017. But even new 3.5" 1TB Barracudas are still CMR.
A smart test might be in order, though. 
I have to apologize, I used a bad search engine, must have been ChatGPT. I looked it up the correct way this time. It is a CMR drive. I have to strike all that I previously said.
