SnapRAID Split Parity Sync Script

SnapRAID v11 adds a sweet new feature, split parity. In the past, adding larger data disk always came with the issue of needing parity disks as large or larger than your data disks. For example, let’s say you add an array made up of (4) 4TB data disks and (1) 4TB parity disk. What if you want to buy one of those 6 or 8TB disks to use in your array? In the past, you could have either chosing to use the new larger disk as your new parity disk, or risk having part of your new disk not protected. With split parity, you could use the new 8TB disk as a data disk and then use (2) of your old 4TB disks, joined together as one complete set of parity (or, you could create parity in this scenario with (4) 2TB disks or even (8) 1TB disks). Pretty neat!

So, this would allow you going forward to add 6 or 8TB data disks and have all your data protected, without having to buy an extra one or two larger disks just to use on parity. Now that we’ve discussed split parity, how can we automate syncing like we did with my previous script? We can’t use that script as is because of the split parity files. So, I already had a modified version of my script, but when mtompkins presented his cleaned up version of my script, I thought I’d extend it for split parity and add a couple of extra functions. I present you now with the new split parity script (this version is setup for dual parity with 4 disks setup to complete split parity).

As a sidenote, I would love it if someone could provide a BASH method to read the snapraid.conf file and automatically build the array rather than having to manually set that up in the config. I fear with split parity, complex grepping may be over many user’s heads.

Here’s how I have the parity files setup from this example in my /etc/snapraid.conf file.



I love learning new things and trying out the latest technology.

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3 Responses

  1. woodensoul2k says:

    Hey Zack, it is still possible to use this script for just a standard dual parity setup? I plan on eventually using a split parity in the future but for now I was just wondering if I could use this new script after upgrading to Snapraid V11. I’m using your older script at the moment on Snapraid V10.

    • Zack Zack says:

      Great question. You can’t just drop this in and have it work, but with a very small modification, it should work fine. You would need to remove these lines.

      and replace them with something like this instead.

      or… if you have dual parity…

      You just need to adjust the names of the parity files that you have setup in your snapraid.conf file, and that should be it 🙂

  2. woodensoul2k says:

    Thanks for the easy explanation. Can’t wait to give it a go.

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