Adding drive to SnapRAID + aufs pool later?

thefivetheory · 11. Mai 2014

I apologize if this has been answered already. I tried searching but didn't find answers to my question.

I'm planning on migrating from WHS 2011 to OMV. I have been using StableBit DrivePool and love it. From what I can tell, the "best" solution for me is going to be SnapRAID plus aufs for pooling.

I've got 4x 3 TB WD Red drives. I am able to get my data onto a single drive by removing the other 3 drives from the StableBit pool (after removing all duplication). That said, I'm left with one NTFS disk that will have my data on it. I can go two ways here: a) further move that data to a few WD Green 2 TB drives, then create a 4-drive pool using SnapRAID and aufs, and copy the files back over, or b) create a 3-drive pool, copy my files over, and then format/add the 4th drive to the pool.

Option b) seems a bit easier in that I don't need to bust out some old 2 TB drives to hold the data in the interim, but I'm not sure if it's easy to add a 4th drive to SnapRAID and to aufs.

What would the general suggestion(s) be here?

Many thanks!

thefivetheory · 12. Mai 2014

I believe I figured out the answer to the SnapRAID part... shouldn't be an issue -- I'm still wondering, though, if adding a drive will be difficult within aufs. I'll probably just try it and see what happens.

davidh2k · 12. Mai 2014

It's suggested to try those scenarios in a VM first. If you screw up there you can still retry.

Greetings
David

ryecoaaron · 12. Mai 2014

Yes, you can add drives anytime to aufs. aufs doesn't do any kind of balancing to existing files. So, it will keep writing to the drive with the most free space.

thefivetheory · 12. Mai 2014

Thanks guys, I appreciate it.

I spent the evening reviewing other forum posts and now I'm leaning more toward greyhole instead. From what I can tell it seems like it's more similar to what I'm used to (StableBit DrivePool on WHS 2011). Probably will spend more time researching first.

I know this has been answered before, but just to confirm... greyhole should give me *more or less* the same basic functionality (redundancy + pooling) as SnapRAID + aufs, right?

ryecoaaron · 12. Mai 2014

Yes.

thefivetheory · 12. Mai 2014

Thanks for the quick response!

Okay, so... given that they're similar, and plugins are available for either option, is there a general recommendation for which makes more sense?

I saw in another thread you mentioned SnapRAID + aufs was good for more static stuff like a media library; I used my WHS box for pretty much 2 things: 1) a home file server and 2) running Plex Media Server. What do you consider "static?" We regularly archive photos, music, as well as miscellaneous files (ISOs, installers, documents) to the WHS box in various shares.

If there was only one option or the other I'd probably be ready to move forward but since the two are so similar (at least for my purposes, it seems), I'm still not certain which is the "best" for me. Most likely I don't fully appreciate or understand the benefits of one over the other... so I greatly appreciate your help!

Also, I'm really impressed by OMV so far -- what a huge improvement over WHS.

davidh2k · 12. Mai 2014

Wait a sec, Greyhole has no parity like SnapRAID has, don't mix that up. Greyhole mirros files multiple times (can be set individually for each shared Folder). SnapRAID builds a parity for all files. Those are two totally different ways.

Greetings
David

ryecoaaron · 12. Mai 2014

They do things differently but still accomplish similar ideas - redundancy and pooling. And notice I didn't say backup

I think Greyhole is better for files that change often. snapraid+aufs will only create parity and therefore redundancy when it is scheduled. Greyhole is constant. So, if you have movies, photos, music, isos... You probably aren't editing them and the parity doesn't need to updated very often. If you have documents, spreadsheets, other files in constant states of change, etc where you may lose an edit or three, greyhole is the better idea in my opinion.

thefivetheory · 12. Mai 2014

That is incredibly helpful, thank you!

So yeah, I think snapraid + aufs does make more sense for me since none of the stuff is used for editing. And I'm planning to continue to use CrashPlan for backup (I saw tekkbebe's posts about the possibility of a plugin in the future for the Pro version, that would be awesome).

Thanks again for the help, both of you.

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