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Best practices for System Dataset Pool location

zeca

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#1
From what I've read, by default the System Dataset pool is the main pool.
In order to allow the HDDs on that pool to spin down, can the system dataset be moved to say a USB pen?
Even to the freenas-boot - perhaps periodically keeping a mirror/backup of that drive?
 

Heracles

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#2
Hey Zeca,

Actually, you probably don't want your disks to spin down. When they do, they end up spinning down and back up all day long. You will ruin your disks in no time doing that. A hard drive is meant to stop and restart only so many times. It is fine for a desktop to spin down because the disks will not start for hours and hours. But for a NAS, every network activity is subject to re-start the disks and often, they will restart every few minutes.

To have the system dataset in the main pool also helps you recover your system's data from the pool itself and not from the boot disk. So that is a second reason to keep it there.
 

garm

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#3
Let go of the world you knew young padawan. The ZFS handles the mirroring of drives. Do not let spinners stop, the thermodynamics will weaken their spirit and connection to the ZFS. USB is the path to the dark side, the ZFS is best channeled through SAS/SATA and actually prices of SSDs are down to thumb drive prices even if you don’t look at per TB price..
 
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#4

zeca

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#5
Let go of the world you knew young padawan. The ZFS handles the mirroring of drives. Do not let spinners stop, the thermodynamics will weaken their spirit and connection to the ZFS.
I am a bit worried about that myself. I've had these 4 drives running 24/7 plugged in to a UPS for about 4 years or so, and so far only 1 has died - replaced it this week.
In order to minimize stress on the hdds and protect that pool from direct access by clients on the LAN, I was considering keeping the same data on the SSD pool. The SSD pool would take snapshots every 1 hour and keep them for only 3 days. Then every 2 days the HDD pool would turn on, run Syncthing (more on this below), mirror changes that occured on the SSD pool and then go back to sleep.
This hdd pool currently takes snapshots every 1 day, keeps them for 2 weeks, then only one every 1 month, then 3 months, 6 months, 1 year. I would change the 1/day to 1/week, 1 per month, etc

I figured a 2 day difference/staggering between the HDD and SSD pools would be enough to detect a Ransonmware attack. Maybe this interval should be longer?

Anyway, back to the point of wear/tear, my reasoning was that by only spinning up once every 2 days and running for a few hours, the trade-off between spin up/down cycling and hours running (as well as power/Temp. saved) would be beneficial.
What do you think?

ps: my CLI-fu isn't enough to master RSync (I've had problems keeping the FreeNAS hdd pool in sync with a local QNAP NAS), so I'll just go for a simpler GUI-based alternative for syncing. I've been reading about this and it's hard to decide between Syncthing, Seafile and Resilio as I have 0 experience with any of them. Since the paid versions aren't too expensive, I wouldn't mind paying if I have to. My list of priorities is data integrity; GUI-based/ease of use; availability in FreeNAS, QNAP, Windows; Low maintenance.
Which would be your preferred solution?
 

Heracles

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#6
Hey again Zeca,

Your plan looks like very complicated and again, will not be that good for the hard drive. To heat up and cool down, just like spinning up and down, is not good either. The best thing for HDD is to stay up, spinning and hot all the time.

SSDs do not have this problem, so if you can fit your entire data in SSDs, you will be good for that. Still, SSDs are not forever themselves and will suffer differently.
 

zeca

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#7
And how about the original question of moving the System Dataset to a dedicated fast USB3 pen. What would be the problem in that - perhaps even mirroring it to a second/backup usb pen? With so many available USB ports on the motherboard, it would be a nice way to use them and keep the System Dataset separated.

How large would the USB pen have to be?
 

Heracles

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#8
Such a thing is of no use without a goal to achieve. What do you try to achieve by moving the system dataset out of the main pool ?

To let the main pool's drives spin down ? Bad idea
To let the main pool's drive cool down ? Bad idea
To save space in the main pool ? Bad idea (system dataset is very small, so no benefit here)

Because there is no benefit doing it, doing so remains a bad idea...
 

zeca

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#9
Such a thing is of no use without a goal to achieve. What do you try to achieve by moving the system dataset out of the main pool ?

To let the main pool's drives spin down ? Bad idea
To let the main pool's drive cool down ? Bad idea
To save space in the main pool ? Bad idea (system dataset is very small, so no benefit here)

Because there is no benefit doing it, doing so remains a bad idea...
I agree with you.
But there is one benefit though. I intend to expand the current 4x4TB Z2 to 5x4TB Z2 as I have an extra 4TB lying around, so since there's currently no support for ZFS expansion, the pool needs to be destroyed at some point. By keeping the system dataset in a USB drive, it's separate from any pool, thus allowing more freedom as to what happens to the pools, no?
Are there any downsides to using a USB drive that I'm not seeing?
 
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#11
What size/type of data are we talking about - eg virtual machines plugins, etc would all run from that system dataset?
I could put a small 40GB SSD to use by connecting it to a usb port for that (this way I'd save SATA ports).
 
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