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

TrueNAS General
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1

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.

1 Like
3

Thanks,

So if I were to put use standby on Pool3, what APM should I use on it?

  • Level 1 - minimum power usage with spindown
  • Level 128 - minimum power usage with no spindown
4

Seagate drives do not respond to the APM commands. You need to use Seachest to change the settings.

https://forums.truenas.com/t/hdd-errors-in-truenas-but-tests-passed-in-seagate-seatools/50965/6?u=krill

5

Level 1.

If they do not spin down, usually, it is because you have the boot pool set on this pool. Move it to a safe pool of SSDs.

6

Do you mean that the “System Dataset” might be located on that pool (which then prevents it from spinning down) ?

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Exactly. That one. However, I understood that if you loose the data of this dataset, it might get complicated, so it is preferable to have it on a mirrored (or redondant pool so you not loose it)

8

I’m by no means an expert, and maybe other gurus will chime in, but as far as I can tell the situation is this: The system dataset stores logs, statistics, and some service data (e.g., Samba DB), but no user data. If the pool is lost, it’s inconvenient but not critical – TrueNAS and your data pools remain intact. As far as I understand, in the past the dataset was often kept off the boot pool because it typically was resided on unreliable media like SD cards or USB sticks; nowadays, for boot pool often SSDs are used, which are much larger and more durable, easily handling the additional wear from system dataset writes.

9

I tried out this feature when I first built my Electric Eel system last year, and found that the drives did indeed spin down after the inactivity time, but they’d spin back up many times throughout the day, because TrueNAS runs frequent short SMART tests on the drives which can’t be disabled or delayed.