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ZFS or SnapRAID

Posted: October 30th, 2013, 11:16 am
by phigo
Hi there, I stumbled upon this fantastic site while researching ideas for my home server. I've bought (and am awaiting delivery of) all of the bits that I'll need (I already have a box with suitable mobo/ram/cpu but I've got 8 x 4tb drives, a pci-e 4-port sata card and an ssd incoming).

I *did* have a pretty clear idea of what I wanted to do. The plan was to put Mint on the box (this is my first Linux adventure and I've read many good things about Ubuntu and Mint especially from a noob pov) and then to use zfs to put the disks in a raidz array.

Now I'm reading about SnapRAID and KVM's (in the virtualisation sense) and thinking that running Ubuntu Server at the core would be a great idea and then maybe a Mint VM on top of that? I chose Ubuntu and Mint for the aforementioned usability reasons but also because I've found Ubuntu versions of packages I currently use on the box in win7 (mostly Handbrake and jdownloader).

In my planning, I went from RAID cards (LSI, Highpoint etc) straight to ZFS and hadn't heard of FlexRAID or SnapRAID until I saw this website. So, I guess the main point of this thread is: SnapRAID or ZFS? I've seen the comparison on the SnapRAID site but does anybody have real world experience with both?

Anyway, thank you very much for this guide. It's really incredible how you've explained everything. I consider myself very proficient in a windows environment but completely out of my depth in anything else. I also very much like your thin client idea but that's a project for a later date!

Edit - I should point out that I'm approaching this with 8 new (obviously empty) drives so the fact that I can put SnapRAID into use on a drive full of data shouldn't be considered a benefit (as awesome as it is) in this scenario.

Re: ZFS or SnapRAID

Posted: September 15th, 2015, 10:20 pm
by kaudley
I run Ubuntu Server 14.04.3 with ZFS on 8 3TB Drives setup in a RAID 10 Mirror.

I can tell you that KVM Performance is very good using virtio drivers for storage and network on either a .raw or .qcow2 vm file. I use writeback and lz4 compression on the file - ensure you have some sort of UPS if you're using writeback or you could lose data/corrupt your VM File in an unclean power off.

This setup works really well - if watching previously recorded video, it's fast, resilient and reliable. The only issue I have come across so far is the combination of MythTV in a VM, recording to and NFS share on the host ZFS filesystem. When watching *live* video, or video in the process of recording - it will stutter and skip. It's just noticeable enough to be annoying and it's a reproducible issue - I attribute it to the COW (Copy on Write) nature of ZFS and accessing the file through NFS while it's being written to disk. The issue seems dramatically improved if you use Samaba on the host instead - but I still notice it when watching in progress or "live" TV.

I have not yet tried BTRFS to see if the same issue exists as I'm not ready to trust my data to BTRFS yet - but I'd welcome comments from anyone who has tried the combo of MythTV VM + Host NFS + Host BTRFS to here your experience.

ZFS is awesome - I would urge you to run mirrored vdevs over RAIDZ though - look here for the reasons as to why http://jrs-s.net/2015/02/06/zfs-you-should-use-mirror-vdevs-not-raidz/

ZFS or SnapRAID

Posted: March 29th, 2016, 7:48 am
by Rolandsr
In searching the forums, I stumbled on numerous posts defining ECC as a definitive requirement for ZFS.

When earlier this year I had "classic" raid issues, I switched to ZFS based on suggestions on this board. I guess I didnt do enough homework, as I have and always have had non ECC RAM.

My RAM is CMV4GX3M1A1333C9, 24GB sticks.

QUESTIONS:

1 Am I, and how badly am I, screwing up my ZFS backups?

2 Buying new RAM not being an option cost and also the mobo manual says non-ecc, should I go back to "classic" raid instead of ZFS?

Re: ZFS or SnapRAID

Posted: September 7th, 2016, 2:05 am
by kaudley
Sorry for my very late reply - I have just now seen this. ECC Ram while nice in a home environment probably won't hurt if you don't have it.

There are many discussions - specifically on the freenas boards wherw a particular zealot, I think his handle is cyberjerk or something like that ;) where you'll hear "if you run zfs without ECC RAM you're DOOMED!!!!"

Allan Jude has talked about the benefits of running ECC RAM and the cons - I'm quite comfortable running without it. Recently I have moved my all my data to BTRFS in a raid10 type setup and so far I've been quite happy with it... I began to wonder about the status of ZFS and the CDL license issues that will never see it in the kernel like btrfs is - I haven't had any issues as of yet and I actually find system tasks like scrubs to be much quicker.

Do some reading but don't buy into the zealot above - he's mostly just an ass that thinks every home user should run enterprise grade hardware....

Re: ZFS or SnapRAID

Posted: May 4th, 2017, 5:20 pm
by LulaNord
Hi...i am a new user here. In my case the only issue I have come across so far is the combination of MythTV in a VM, recording to and NFS share on the host ZFS filesystem. When watching *live* video, or video in the process of recording - it will stutter and skip. It's just noticeable enough to be annoying and it's a reproducible issue - I attribute it to the COW nature of ZFS and accessing the file through NFS while it's being written to disk.