Things to know before enabling 'HDD Standby' and 'Advanced Power Management'?

TrueNAS General
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Hello,

I have 3 pools on my Truenas Scale and wanted to do some power management with HDD Standby and Advanced Power Management (APM).

  • Pool 1 = 1 SDD - Stripe - For apps
  • Pool 2 = 2x 4TB Ironwolf Pro - Mirror - Media storage and other big stuff
  • Pool 3 = 3x 500GB Toshiba something - RAIDZ1 - Lots of smull stuff, personnal storage, access via SMB.

I wanted to activate HDD standby and advanced power managemnt on them but never used them before.

I know that you shouldn’t use them on active disks but what is considered an active disks? Is it writing, reading or both?

For example, I have a qBitTorrent server on Pool 1 but reads data on Pool 2 because all my media is there. I am seeding at all times, everyday.

Can Pool 2 be in standby then? Or use APM?

Pool 3 is barely used but sometimes I need to access data in it via SMB. Sometimes multiple times a day or nothing for multiple days.

Thanks for any tips, guides or ressources you can give me.

2

From my personal (and small) experience, I have 2 pools, one of SSDs (2x1TB mirrored), and one of HDDs (5x4TB RAIDz1, with one additinal 1TB L2ARC SSD, and 2 of the HDDs used as spare for now, until I need more storage).

I have set the SSDs with no power savings, as they are continuly used by containers, and they are SSDs, so use less power anyway.

On the HDDs, I set full power saving mode, with spindown after 60min (smart check not disabled !). They definitly spin down when not used, and the ARC helps not to access the files on them. L2ARC helps also a bit I think. They are most of the time not spining up, and I think I have something like one or 2 spinup a day, 5 in total if I use the system, and I have set spindown to 60min, so that they don’t spin down during active use.

In your case, you should be able to spin down the pool 3, but not the other ones.
For seeding, what I did, was to use the SSD pool for downloads and seeding, and once done, it is copied to the HDD pool. this way, I am not continuly using the HDD pool : I use it only once.

For SMB, it works. You have to wait for the HDDs to spin up if you are doing something, but opening a file in ARC works instantly, same for navigating in the folders which does no spin up.

I Nextcloud access it as well, and for that one, it works the same way as for SMB (since it is accessing the SMB share). However, when sharing a file with a link, it works less great : the file has to be opened a second time, otherwise you get a white page if you open a pdf for example.

I hope this helped you a bit.