Want some advice on mirroring boot-pool

[tsm37]

I'm thinking whether I should mirror the boot-pool drive, which is currently on a single small capacity SATA SSD. I'm on a test environment right now but considering whether I should mirror the boot-pool drive when I convert my test truenas scale box into a live production environment. I'm aware that as long as I have the config file is backed up somewhere, I can just replace the the existing boot-pool drive with a new drive, just do a fresh install of truenas scale on that new replacement drive and then restore the config file. It doesn't sound that difficult.

My ask is that I want to hear from you guys whether or not you mirror your boot-pool drive. Yes, why? If not, why? How did you draw the conclusion of mirroring the boot-pool or not. Your responses will help me think through this matter. Thank you

 

[Arwen]

I would make the decision based on several questions:

• Do you have easy access to your NAS?
  Meaning is it in a local or remote location?
• Do you need / want more up time?
  Meaning do you serve others, and around the clock?
• Last, do you just want your NAS to work for years without much maintenance?

If I had both money and storage ports, I would mirror the boot-pool just to eliminate the lost time of dealing with single boot device failures. My tolerance for hardware failures has dropped over the decades.

 

[tsm37]

Thank you. To answer the questions:
-Do you have easy access to your NAS?
Yes, I do

Meaning is it in a local or remote location?
Local

-Do you need / want more up time? Meaning do you serve others, and around the clock?
I don't need to serve a lot of people, but more uptime is always good.

Last, do you just want your NAS to work for years without much maintenance?
Yup, I think this one is a key consideration. I'm coming from Synology, and my old Synology box has served me well for over 6 years without any issues at all, and it was running 24/7 without any hiccups. So yes, I would like to have the same experience in Truenas Scale and understanding Truenas Scale requires skills and knowledge.

 

[Arwen]

Oh, one other point for people that may not understand what Mirroring gets you.

Assume a 2 disk Mirror pool, (like a boot-pool). If you get a bad block, instead of reloading the OS and restoring the configuration, ZFS will auto-correct the bad block. This assumes that the Mirror devices have spare blocks available. ZFS would read a block, (either during normal operation or during a scrub), and if it finds a bad block, it will read the block's Mirror. Then re-write the bad block with good data. Thus, fully restoring redundancy.

Thus, even if you get bad blocks on a Mirror pool, server stays up.

 

[olddog9]

Arwen,

"If I had both money and storage ports, I would mirror the boot-pool just to eliminate the lost time of dealing with single boot device failures. My tolerance for hardware failures has dropped over the decades."

Amen to that !

 

[Constantin]

Sadly, the GUI will not allow you to mirror the boot pool more than 2-ways. This is frustrating in case one would like to make copies for offline storage with a known-good boot drive. Doing it via the CLI is potentially possible but that may break every time the system is updated.

 

[tsm37]

Oh, one other point for people that may not understand what Mirroring gets you.

Assume a 2 disk Mirror pool, (like a boot-pool). If you get a bad block, instead of reloading the OS and restoring the configuration, ZFS will auto-correct the bad block. This assumes that the Mirror devices have spare blocks available. ZFS would read a block, (either during normal operation or during a scrub), and if it finds a bad block, it will read the block's Mirror. Then re-write the bad block with good data. Thus, fully restoring redundancy.

Thus, even if you get bad blocks on a Mirror pool, server stays up.

Thank you - now I'm completely sold of the idea mirroring boot pool.