Does running a parity check cause a performance issue in SageTV

[wayner]

I have just built a new server with an 8TB parity drive, and data drives of: 1x8TB, 2x4TB. A parity check in this system seems to take from 18-24hrs. I have an old system with a 4TB drive and parity checks on that system take about 12 hours so around 24 hours seems reasonable.

But while the parity check is running I experience significantly degraded performance. Here is one example - when I use SageTV to play back video files the playback can be herky jerky at times. When I try to skip forward over commercials it takes the system several seconds to catch back up and I may see a spinning circle for a while. If I pause the parity check then these problems completely go away.

Is that expected performance? Or do I have something wrong on my system? I didn't notice this issue on my old system, but the parity check ran at a time when I rarely used SageTV as it started around midnight and was done by noon.

[KeithAbbott]

I get similar issues when running my monthly parity check. The "Parity Check Tuning" plugin is your friend. I have set my parity check to begin on Monday at 12:01am, then it pauses at 5:30am. The next morning, it resumes at 2am, and then pauses again at 5:30am. Rinse and repeat. It is finished by 5:30am Friday morning, without really causing any playback issues because no one is watching television during those hours. I also don't really record any shows during those times, so I don't know if recordings are impacted or not.

Also, if you haven't installed it already, check out the "Fix Common Problems" plugin. It helps me keep Unraid error free.

[wayner]

Thanks Keith, I just set that up. I will do something similar so that it runs overnight, but stops in the morning.

Just one clarification. In this plugin's setup screen there is a top portion called "Parity Check" and then a lower portion called "Parity Check Tuning". If you are using the tuning do you have to set both areas?

And these plugin seems to replace the core Scheduler Settings screen, is that correct? So I only have to worry about setting the parity check in this plugin and I don't have to setup the parity check in the "core" unRAID screens, correct?

And one further question. Do you use the Backup plugin as well. Do you have to worry about the backup conflicting with the parity check? This wasn't an issue for me in the past as I ran the parity check every Sunday morning at 1am and then the backup on Monday at 1am.

[KeithAbbott]

I could be wrong, but I think all the plugin does is adds a Parity Check Tuning section to the settings page. The Parity Check section is just the stock Unraid section. The top section specifies the time that the parity check is started, the Tuning section is where you specify pause and resume times.

I use the "CA Backup / Restore Appdata" plugin, not sure if that's the one that you are referring to or not. I have been manually initiating it, since up until now I have been running separate dockers for OpenDCT and SageTV. I want to be able to control the order of the shutdown/startup of these dockers, so I just do it manually. However, once I migrate over to Jusjoken's single docker container with OpenDCT and SageTV baked in, I will set it up to automatically run. I'll just find a time outside of when the parity check runs.

[wayner]

Yes, that is the backup. The downside to it is, as you say, that it needs to stop the dockers.

Regarding parity check - when I go into the Settings-Scheduler it brings up the Parity Check Tuning page so it looks like it replaces the Scheduler and takes care of setting up Parity Check plus Mover.

[KeithAbbott]

Weird. Mine also has a section for Mover Settings, and a section for Fixed Schedules below the Parity Check Tuning section. The Fixed Schedules section is because I installed the Dynamix Schedules plugin, if I recall correctly.

[wayner]

I started a thread on the unRAID forums on this issue and some of the experts have responded there: https://forums.unraid.net/topic/1186...while-running/

[stuckless]

Originally Posted by wayner

I started a thread on the unRAID forums on this issue and some of the experts have responded there: https://forums.unraid.net/topic/1186...while-running/

Thanks for asking and sharing that thread. Because I'm not recording much I don't usually see much of a performance issue, but, that might change in a few months.

I have a 8tb parity with 8tb, 4tb, and 4*3tb data drives (24tb total) and my parity check ran for 19 hours.

Last check completed on Sat 01 Jan 2022 07:03:31 PM EST (fifteen days ago)
Finding 0 errors Duration: 19 hours, 3 minutes, 30 seconds. Average speed: 116.6 MB/sec

I noticed you have a 8tb parity and no 8tb data drive... is that just so that you can grow into it later? I only upgraded to 8tb parity over xmas... took several days and I had to rebuild after inserting drives, etc.

[wayner]

Originally Posted by stuckless

I noticed you have a 8tb parity and no 8tb data drive... is that just so that you can grow into it later? I only upgraded to 8tb parity over xmas... took several days and I had to rebuild after inserting drives, etc.

I don't know if you were responding to me, but I do have an 8TB data drive as well as two 4TB data drives. 8TB seems to be the sweet spot right now as I got my 8TBs for C$175 a couple of weeks ago. One of my 4TB drives seems kind of flaky so I might pull it out. But 12TB is enough data space for me right now as I am not growing my data that fast due to the current situation where most of the good content is on streaming services. And the bulk of my SageTV recording is sports which don't stay around very long.