Some questions about new install

[vampyren]

Hi guys,
I am getting started with my TVS-h1688X (QuTS Hero h4.5.4.1771) and i see this folder "homes_used_by_pool_1".
I disable home folders for users but this is still there. What's the purpose of this? can i remove this or is this used by anything?

Also i dont get the point of snapshot to be honest. Considering i might fill up the NAS , i cant take snapshot of the size of the NAS as it grows.
Maybe if i had say 2 of the same NAS and storage but then again thats the point of having RAID6 to cover for 2 disk failures.
Maybe i'm missing the point but not sure why i would have it enabled even?
Or maybe snapshot is like taking an image of a shared folder so i can simply backup a folder as a whole so that i can later import it more easily? (like ziping a folder sort of)

Appreciate all the help setting up my new NAS.
I got 2x512GB Samsung 970 EVO M2 that i have now configured as RAID1 for my pool1
Also i got 6x16GB WD RED that i have configured as RAID6 for my pool2 (here is where i create my shared folders but various backups).
Its been a while i created shared forlders so i got tons of questions when doing so now. No idea if i did it right. Please see the attachment for summary of one folder, for instance i selected Standard on I/O mode as i have actually VM files in that folder.
But i will have like tons of pictures in another so i might select differently (not sure it matter allot).

Also No idea if Compression makes sense? its enabled by default so i did not change it!

[Thisisnotmyname]

snapshots don't create duplicates of everything, it is a differential system. In other words, once you've snapshot then it creates a new instance for anything that changes on a go forward basis. You make a change to file XYZ then only file XYZ gets a new copy. This gives you a way of rolling back to the previous snapshot version should you need to.

Not sure what virtualization engine you are using, is your VM's virtual hard drive block size 32K? I'd match up the ZFS recordsize with your VHD block size for that share (or as close as QuTS will allow you to). For shares holding images and such I would not, I'd go with a much larger recordsize there (128k is as large as the limited version of ZFS QNAP has put forth will allow - or at least via the Web UI, I haven't dug into ZFS config via CLI on QNAP yet). I also wouldn't use compression on the volume holding your VM's VHD but I WOULD use compression everywhere else. Standard IO is fine across the board, situations are limited where you'd want to force synchronous. Personally I turned off fast clone, I just don't have any use case for it but your mileage may vary.

[vampyren]

Thanks for the info @Thisisnotmyname !
I get that the snapshot uses differential after the first snapshot but the end result is that the original + snapshot + differential will be together double the size right? And i already got raid6 to cover data loss. That was my point.

In regard to virtualization i'm using the Virtual station to create windows VMs and later linux VM. I think i will go standard as you say for the rest as well.

[Thisisnotmyname]

I'm probably not explaining it well, QNAP has a page on it that might help though...

https://www.qnap.com/en-us/software/snapshots

Your concept of "original + snapshot + differential" is incorrect though. It's just "original + differential(s)". If you have 100TB of data and make one snapshot but then never modify anything again your total usage remains 100TB (minus some mostly inconsequential overhead, certainly nowhere near doubling).

There are some very pedantic people in these forums so before you get the "RAID is not backup" I'll point out some subtleties to your "RAID6 to cover data loss". RAID6 provides redundancy in the event of the loss of up to two drives. Some things it does NOT protect against:

- theft of your NAS
- a fire in your home or business
- ransomware
- accidental deletion of a file
- accidental overwrite of a file
- file system corruption
- hardware failure other than disks that causes bad writes

Snapshots can protect you against some of those (ransomeware, accidental deletion, accidental overwrites - you could roll back to the prior snapshot for any of those), external backups can protect you against others (file system corruption, theft of your NAS - things you need to start fresh with and restore all data), OFF SITE (e.g. cloud) external back ups can protect against others (fire - anything that would also destroy your external backups that were in the same location). RAID6 isn't a catch all, it protects against a specific type of data loss but not all data loss. For data you can't stand to lose make sure you also have an off site backup.

I'm glad you are using RAID6 as well, do keep in mind that when you lose a drive the other drives in the array are often close to the same age and wear. The act of rebuilding the array can itself lead to an unrecoverable read error on another drive. In RAID5 where you have only one parity drive that would cause you to lose the entire array. RAID6 you can survive on other drive, don't hold off drive replacement if you do lose one though, lose a second and you could easily lose a third in the rebuild.

[vampyren]

@Thisisnotmyname
Thanks for the detailed explanation. I think i get your point now. Its more like appl'e time machine.
And just as you say Raid6 wont cover all things. I do have backup to the cloud for my most important stuff like family pictures so that part i'm covered. Also i take backup on external drive time to time.