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First timer storage/pool questions

Western Digital Drives - The Preferred Drives of FreeNAS and TrueNAS CORE
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petesmc

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Hi,

I've just ordered all the components for my first FreeNas file server but I have a few questions regarding optimal pool set up. I have capacity in my case for 8 hdds + nvme boot drive. As such, i have ordered 9x 8tb WD Red drives (one cold spare) and have now started thinking about pool setup. I believe my sensible options are RaidZ2, RaidZ3 and mirrors. I have heard of a term striped mirrors, but i really am not sure what that means. My data is separated into entertainment media (backups of dvd's and blurays) and personal media/documents. It is critical that the personal media/documents remains safe, but the entertainment media can be lost (would be annoying and a waste of time).

I already have a local backup of the personal media, as well as a cloud backup, but will be further protecting the entire FreeNas server by duplicating to another remote location eventually. Given that i have multiple backups, and don't mind potential long resilver times*, i'm guessing that RaidZ2 is probably my optimal balance between redundancy and storage capacity.

*I really don't know how long the resilver times would actually be. Whilst I could tolerate 2-3 days of downtime, i'm not how happy the family would be!

1. Do you agree RaidZ2 is my optimal solution here?
2. Does an 8 drive RaidZ2 even make sense?
3. To confirm, with RaidZ2, i can withstand up to 2 drives failing before full data loss?
4. Given i have two different sets of data, would it make sense to set up datasets for this?
5. Can ZFS do duplication per dataset or just per pool?
6. Performance wise, RaidZ2 would be only as fast as the slowest drive? Does this mean i would struggle running more than 1 stream (not transcoded) of Bluray?


Thanks for the advice in advance

Pete
 

Jailer

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Sep 12, 2014
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1. Yes
2. Yes
3. Yes
4. Yes. Datasets is exactly how you set up separate storage areas on the same pool.
5. Both if I'm remembering correctly
6. You're network connection will likely be the bottleneck. You'll have no problem with multiple streams.

I have heard of a term striped mirrors, but i really am not sure what that means.
It's just more than one pair of mirrors in a pool.

i'm guessing that RaidZ2 is probably my optimal balance between redundancy and storage capacity.
That is correct for your use case.

*I really don't know how long the resilver times would actually be. Whilst I could tolerate 2-3 days of downtime, i'm not how happy the family would be!
Your data will still be accessible during a resilver but performance will be slightly reduced. You shouldn't experience any down time during a resilver.
 
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Stux

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Jun 2, 2016
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You can with stand two full drive losses before the possibility of data loss with Raidz2.

Personally I wouldn't of bothered with the cold spare. When a drive fails I drive to a shop and buy a replacement .

You really still need to burn in your spare as they can become faulty on the shelf.

So, when you have a failed drive, refresh your backup, buy a replacement, burn it in and replace. Your backup should refresh before you lose two more drives ;)
 

danb35

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*I really don't know how long the resilver times would actually be. Whilst I could tolerate 2-3 days of downtime, i'm not how happy the family would be!
The system is not down while you resilver. If your hardware is capable of hot-swap, it need not go down at all. Otherwise, it's down for only as long as it takes you to power down the machine, swap the disks, and boot it back up.
5. Can ZFS do duplication per dataset or just per pool?
Both, but don't. Deduplication takes lots of RAM (seriously, lots of RAM), and rarely provides much benefit over compression (which is enabled by default and is almost free).
 

petesmc

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Finally have the server sitting in my living room and i'm confused as to how i set up RaidZ2 in the GUI. Should it be 1 row of 8 drives, or 2 rows of 4 drives?
 

Ericloewe

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compression (which is enabled by default and is almost free)
In many cases, it is even a net positive, as it can reduce disk accesses required for the same amount of data.

Finally have the server sitting in my living room and i'm confused as to how i set up RaidZ2 in the GUI. Should it be 1 row of 8 drives, or 2 rows of 4 drives?
One row and you have to choose RAIDZ2 from the drop-down menu.
 
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