unRaid Parity Checks, Settings Question

I’m brand new to unRaid. I wanted to setup a schedule to do so. I see some people do monthly, some quaterly. I know it will be up to me on what schedule. Question is on the settings. I’m making the assumtion you would want to write the corrections to the parity disk? What about a cumulative? Pros/Cons to either setting to be yes?

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Cumulative just lets you spit up a check over multiple time blocks. For example you set a check to run once a month and set the cumulative settings so it runs between 1am-6am daily until the check reaches 100%.

As for parity checks in general they basically are just a warning that something is wrong and you need to investigate what caused the errors before you decide if it makes sense to write the corrections. Atleat that’s the way I see it.

So for automated Parity checks I would not write corrections and instead treat it as a warning system of sorts.

Then if you do get errors investigate if it was just a unclean shutdown or something more serious (failing drive, bad ram, ect) before you decide to run a new check and write the corrections or not.

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So for my unraid server I tend to do parity checks every time the server was shutting down incorrectly like on a power outage (never the case) or because unraid crashes (happens from time to time 2-3 times a year). And I also do parity checks before installing or replacing smaller disks with bigger ones. That all leaves to a parity check every 2-3 month which is enough in my opinion especially if you use your unraid server disks only for rare use cases like watching movies and something like that meaning that the disks are spinned down most of the time.

There is also a plugin available in the unraid community app store that allows incremental parity checks so if you want to do them on a regular basis maybe at times when the server is idling that would be a thing to try out.

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Thanks for the info. I’m in a conundrum at the moment. I was at work and I guess we had the power go out 3 different times in a span of 4hrs. I have the server set to restart upon gaining power. So, at this time my parity is valid(green), but have 38,643 errors. I can only assume those came from improper shutdowns. Probably do another parity check? Would those remove the errors?

Its probably safe to assume it was the power outages. You can check if there are 0 disk errors on “MAIN” in the web ui and check SMART info for each disk if you want.

I assume it ran a correcting check and it says.
Parity is valid
Last check completed on “----------------------------------”
Duration: “-----------------------------”
“Finding 38,643 errors”

You can run a non correcting check and see if it comes back with 0 errors to verify nothing is actively causing new errors.

I would also not recommend having it auto start on gaining power. I had some problems with that in the past. Work was being done on the building when I was away and it got powered on and off probably 10-20 times.
Also recommend having a ups just so it can safe shutdown to avoid problems like that.

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Just wanted to do an updated. I re-ran a parity chck and everything came back good, no errors. I change my bios settings to not have the server auto restart when the power comes back on. I have a UPC on my computer. I’ll have to see about getting one for the unRaid server. Thanks the trouble shooting help.