[HowTo] SnapRAID in OMV

Hello all.

I am thinking about migrating from Unraid and I like the look of OMV very much. Having played around with a test system it seems to do everything I require, only problem is that I don't have enough spare hard drives to be able to test out the SnapRAID plugin, hence these questions

My server is turned on only when I need it, serving up films, music, doing photo backups etc...

• With Unraid parity is calculated in real time, but with SnapRAID I understand that a sync command needs to be performed. Creating a Cronjob seems like the way forward, but how does this fit in with a server that isn't switched on overnight? I presume the cronjob will run the next time the server is up, but how long for example, does calculating parity take, say for 10GB of new data?
• Is the plugin robust enough to "set it and forget it" or does one need to keep checking the admin interface or hit the command line every now and then to perform syncing, fixing when necessary etc...
• Data scrubbing. This is new to me. Is it really required and what's involved from a users perspective?

Many thanks!

Thanks for the clear answers.
Yeah I am using the "usual suspect": HP Microserver gen. 8. The reason I am asking is sometimes I run the server up for just 10-15 mins to do some task, if a sync task is taking place how does shutting the server down handle that cleanly? Sometimes with Unraid I had issues if the server wasn't shutdown cleanly and all of the processes correctly stopped, this resulted in kicking off a parity check the next time the server was started.

Cheers.

I'm in the "unRAID -> OMV Migration Club" too!

I've just bought a new data drive, so I'm using this as an excuse to migrate; but I also want to convert my drives from ReiserFS to XFS ( Researched XFS vs EXT4 so any input there is also appreciated!).

My idea is to mount the original drives; use the new drive as a SnapRAID parity disk; sync; re-format the original data drive as XFS; then "fix" the re-formated drive so restore the data; but using XFS as the underlying file-system...

I'm setting up a VM to trial my plan; but I'm going to ask here to save the effort... Should my plan work or is it a big no-go?!

... Well; thats exactly what the sensible head says!! The "too tight to buy a second 6tb drive just after the first to use as parity" head says "Try it!" haha :).

Thanks for your input, and on the ReiserFS issue i posted about the other day; its been sorted in 1.17

SnapRAID 8 has been released. The changelog looks interesting.

I updated to the latest version of the plugin and it seems like the diff script moved locations I can now only find "omv-snapraid-diff" in /usr/sbin -- and when it is executed, it seems to work but also returns this:

"/usr/sbin/omv-snapraid-diff: line 368: [: missing `]'"

Any ideas?

Ok, I did omv-mkconf snapraid and tested it again. Still getting the "/usr/sbin/omv-snapraid-diff: line 368: [: missing `]'". Hmm...anything else I should try?

Sure...

<snapraid>
      <blocksize>256</blocksize>
      <autosave>0</autosave>
      <nohidden>0</nohidden>
      <pool>0</pool>
      <poolname></poolname>
      <syslog>1</syslog>
      <debug>0</debug>
      <sendmail>1</sendmail>
      <runscrub>1</runscrub>
      <scrubfreq>7</scrubfreq>
      <delthreshold>0</delthreshold>
      <drives>
        <drive>
          <uuid>4ad4bd5c-033a-4a72-a926-4390b649db19</uuid>
          <mntentref>f208c447-df84-463b-b76e-5e8b29eed525</mntentref>
          <content>0</content>
          <data>0</data>
          <parity>1</parity>
          <name>Parity</name>
          <label>Parity</label>
          <path>/media/9dcc6289-e96e-442e-af7d-4ca6575d3c6b</path>
        </drive>
        <drive>
          <uuid>8cd44ac1-5d9e-4e6a-b20b-294e037ac36a</uuid>
          <mntentref>17372632-95c4-4845-89d6-0e0dadfafdc3</mntentref>
          <content>1</content>
          <data>1</data>
          <parity>0</parity>
          <name>Disk1</name>
          <label>Disk1</label>
          <path>/media/8dae58b4-c3b5-4f4b-a814-6138c4694e5a</path>
        </drive>
        <drive>
          <uuid>7450c94a-22e9-4452-825d-fe00df0e225d</uuid>
          <mntentref>62505b9f-3474-42a3-a55d-d34affbd436a</mntentref>
          <content>1</content>
          <data>1</data>
          <parity>0</parity>
          <name>Disk2</name>
          <label>Disk2</label>
          <path>/media/2569f21c-d024-4fc8-885d-7ed379ab3c4f</path>
        </drive>
      </drives>
      <rules></rules>
      <percentscrub>12</percentscrub>
      <scrubpercent>100</scrubpercent>
    </snapraid>

Just came to report a bug with $DEL_THRESHOLD. The script runs for me, but delete threshold is ignored in a strange manner - in logs I can see "deleted files (2175) is below threshold (11)", where 11 is my delete threshold.

I updated and tried again, but I get this instead:

/usr/sbin/omv-snapraid-diff: line 370: [: missing `]'