better alternatives to mergerfs/snapraid available?

molnart · Jul 29th 2023

I am going to do significant changes to my OMV setup in the near future, putting it to a entirely new hardware, replacing some disks with bigger ones, etc, and i started thinking about how I could improve my config that is running more or less unchanged since 2018 or so.

Mostly I am wondering, that since OMV recently introduced some interesting btrfs features, do they provide any alternatives to the popular mergerfs/snapraid stack? while those tools work great for my use case, i would prefer a more built-in solution that is not relying on external one-man-show developers (and ryecoaaron getting grumpy when updating plugins ) and potentially could provide a better experience and additional features?

BernH · Jul 29th 2023

If you read about btrfs, it is still in sort of a beta stage and not able to reliably do more complicated drive setups than the equivalent of RAID 0 or RAID 1.

I personally prefer to use mdadm RAID for the more complicated setups for this reason (a RAID 5 in my case), and since I am using it for the complicated setup, I also choose to use it for a simple RAID 1 that I also run.

That said, there is nothing wrong with mergerfs/snapraid to give a similar kind of setup which is also faster to build and potentially less trouble to fix if something goes sideways.

chente · Jul 29th 2023

Quote from molnart

since OMV recently introduced some interesting btrfs features, do they provide any alternatives to the popular mergerfs/snapraid stack?

The alternative that BTRFS offers you in OMV is Raid1, Raid0 or Raid10. Raid5 on BTRFS is still unstable, you can check the BTRFS documentation to verify it. Therefore I doubt that this configuration will be offered in the near future on OMV.

Quote from molnart

i would prefer a more built-in solution that is not relying on external one-man-show developers (and ryecoaaron getting grumpy when updating plugins ) and potentially could provide a better experience and additional features?

I think that you can never avoid it. Central OMV is maintained by one person, votdev. omv-extras is maintained by one person, ryecoaaron. You will always depend on one person no matter what you do at OMV.

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I personally chose ZFS for several reasons. Although the ZFS interface in OMV is not complete, it is developed enough to cover most needs. In any case it is easy to run any CLI commands that may be needed.

You can configure Raid5 with guarantees, which BTRFS cannot.

ZFS has several advantages over mdadm, it is a more modern and developed file system.

mdadm Raid5 also has some problems that are not often talked about, but they are there.

mergerfs mas SnapRaid is very nice on paper, but when something goes wrong you have to be perfectly clear about what you do to recover from a failure. It's not easy. In addition, maintenance requires making certain choices, and getting it right.

But these are all personal choices, this is just my opinion.

molnart · Jul 29th 2023

maybe I should add a few worlds on my requirements

1) ability to use drives of different sizes (currently i have 3TB, 4TB, 6TB and 8TB drives in my setup)

2) ability to simply replace any drive in the system with a bigger one, by just simply cloning the data & extending the partition

3) ability to pull any drive from my NAS, plug it into any random computer and read the data, without having the rest of the drives

4) have some basic recovery options in case of drive fails

currently snapraid & mergerfs fulfills all those requirements. as far as i understood, given the above requirements, RAID, ZFS or any blocklevel solution are not an option as they fail in points 1-3

the only thing coming close seems to be Unraid, but i am not too eager to go that direction

BernH · Jul 30th 2023

You are correct there. Based on your statements mergerfs and snapraid are what you need

ryecoaaron · Jul 30th 2023

Quote from molnart

i would prefer a more built-in solution that is not relying on external one-man-show developers

Better not use OMV then.

Quote from molnart

ryecoaaron getting grumpy when updating plugins

Nice. I have been working on these two plugins for almost a decade. If that doesn't give you a more comfortable feeling, not much will.

Quote from molnart

potentially could provide a better experience and additional features?

While I agree the btrfs experience and features are good, it is better because it offers more features and it is integrated together. Hard to make multiple products work together better than an integrated system. I would be curious what additional features you are looking for?

crashtest · Jul 30th 2023

Quote from molnart

potentially could provide a better experience and additional features?

A better experience, from the user's perspective, usually means easier (less complex) and more integrated. However, since a "better experience" requires more control to keep users from damaging their install, flexibility suffers.
Additional features is, generally, more flexible but it's less integrated and tends to be more complex.

From a development perspective, a better experience is at odds with additional features.

molnart · Aug 2nd 2023

Quote from ryecoaaron

Better not use OMV then.

Nice. I have been working on these two plugins for almost a decade. If that doesn't give you a more comfortable feeling, not much will.

No offense was meant. i am not too concerned about OMV itself and I am perfectly aware that it's a one man show. but adding two separate additional one-man show products with declining popularity (since more people moving to things like ZFS , BTRFS being more "endorsed" by OMV, off the shelf solutions like Synology or moving away from homelabs altogether because they have a life, etc...) makes me more worried. I am perfectly aware of the huge effort you are putting into plugin maintenance, but it also feels its becoming more and more complicated with each change upstream, and one day it may come that maintaning those plugins will be simply too much pain that will be simply not worth it for those few users.

so i was just simply wondering if the users using mergerfs/snapraid are still using it, or have moved on to better solutions. apparently not.

chente · Aug 2nd 2023

Quote from molnart

so i was just simply wondering if the users using mergerfs/snapraid are still using it, or have moved on to better solutions. apparently not.

I would say that in the end it all depends on the money you are willing to spend on hardware and software to watch a few movies, simple as that It is the goal of 90% of NAS users.

macom · Aug 2nd 2023

Quote from molnart

declining popularity (since more people moving to things like ZFS , BTRFS being more "endorsed" by OMV, off the shelf solutions like Synology or moving away from homelabs altogether because they have a life, etc...)

Do you have any indication that this is the case?

skittlebrau · Jan 16th 2024

Quote from molnart

i would prefer a more built-in solution that is not relying on external one-man-show developers

I get where you're coming from, but it's not really any different compared to something like TrueNAS which is owned/maintained by iX Systems. They as a company could go bankrupt tomorrow or could be acquired by a larger company that takes away the free version like what Broadcom did to VMWare yesterday. While the filesystem itself is portable, there aren't that many other NAS-focused distros like OMV that make ZFS management easy for people who aren't comfortable with the command line.

SnapRAID + mergerfs is a combo that's been used by many people over many years. It's certainly not perfect, but they and OMV are under active development and that's the main thing.

Whatever you choose, as long as you're in control of your data and have it backed up, then you have the flexibility to migrate to a different storage solution in future.

jollyrogr · Jan 17th 2024

Snapraid and mergerfs is still the best in my opinion. If something else did become available, I would be skeptical of it until some track record of success had been established. Snapraid is mature and proven. Off hand I can't think of any feature that's missing.

ryecoaaron · Jan 17th 2024

Quote from jollyrogr

Off hand I can't think of any feature that's missing.

Support for btrfs subvolumes is something that will probably come up more often now since OMV is creating a subvolume for a sharedfolder on btrfs. Unfortunately, that support needs to be added to snapraid.

Krisbee · Jan 17th 2024

Quote from jollyrogr

Snapraid and mergerfs is still the best in my opinion ...

So what happens if your parity drive dies along with a data drive? Just kidding, but I've always looked at this as horses for courses. Did anyone ever try to chart the pros and cons of the various methods of handling multiple drives in OMV alongside criteria for deciding best choice?

jollyrogr · Jan 17th 2024

Quote from Krisbee

So what happens if your parity drive dies along with a data drive? Just kidding, but I've always looked at this as horses for courses. Did anyone ever try to chart the pros and cons of the various methods of handling multiple drives in OMV alongside criteria for deciding best choice?

I recover both. I have two parity drives and 8 data drives at the moment so I can recover from a failure of any two. As my array expands I'll probably look to add a 3rd parity drive.

Krisbee · Jan 17th 2024

Quote from jollyrogr

I recover both. I have two parity drives and 8 data drives at the moment so I can recover from a failure of any two. As my array expands I'll probably look to add a 3rd parity drive.

Any two? Two dead parity drives?

ryecoaaron · Jan 17th 2024

Quote from Krisbee

Two dead parity drives?

Just rebuild your parity. No data lost.

snapraid still is not backup. But at least you don't lose everything if both parity and one data drive fail.

Krisbee · Jan 17th 2024

Quote from ryecoaaron

Just rebuild your parity. No data lost.

snapraid still is not backup. But at least you don't lose everything if both parity and one data drive fail.

It wasn't really a serious question, but I wonder what would happen if your had this sort of failure mid sync?

jollyrogr · Jan 17th 2024

Quote from Krisbee

It wasn't really a serious question, but I wonder what would happen if your had this sort of failure mid sync?

SnapRAID

What happen if a disk breaks during a "sync" ?

You are still able to recover data. In the worst case, you will be able to recover as much data as if the disk would have broken before the "sync". But if the "sync" process already run for some time, SnapRAID is able to use the partially synced data to recover more. To improve the recovering you can also use the "autosave" configuration option to save the intermediate content file during the sync process.

So I interpret that as you can recover 100% of synced data and as much as had been synced during the sync process until the disk failure. This is why I copy files to the array then sync before removing the original from desktop/laptop.

What happen if a disk breaks during a "sync" ?

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