High Average Load during recording

losangeleskingsfan15 · August 23, 2021, 12:57am

Hello!

I recently have been running into an average load issue. It seems like during recording, regardless of how many tuners are active, the load on the CPU would spike past 100% which would cause playback on my Ipad to be interrupted until it drops below 100. These spikes tend to happen in a random fashion during recording with the load sometimes dropping to 10% which would increase slowly past 100. I checked my CPU usage on my linux machine and it shows low cpu usage with occasional spikes during the high load. How can that be? Do I need a better CPU? Is anyone having a similar issue? Thanks.

Specs:
ASUS All Series
linux ubuntu
20.04 (kernel: 5.11.0-27-generic)

AMD Athlon 5150 4 core
8GB DDR3
Crucial M4 128GB SSD for OS
Western Digital Green 3TB HDD for storing recordings
Tuner is a HDHomeRun Flex 4K with 4 tuners available attached via ethernet to home network (linux machine is also hardwired)

Macnbaish · August 23, 2021, 1:15am

IO wait is included in the load figure, so it’s possible that the disk itself may be to blame. That would be my first guess, based on the data you provided. Can you check at the time of the issue and see how busy the disk is? That would confirm the theory.

racameron · August 23, 2021, 1:23am

I agree that the bottleneck is most likely your drive.

losangeleskingsfan15 · August 23, 2021, 1:31am

Oh wow, i didn't know that figure included the entire system. Makes a lot of sense. I'll check the busy status.

losangeleskingsfan15 · August 23, 2021, 1:56am

i went ahead and analyzed the real time disk read/write, lo and behold it was writing real slow. It matched exactly with the load figures.

Is my hard drive dying? A working one shouldn't perform like this, no?

Macnbaish · August 23, 2021, 2:12am

Hmm yeah something is going on. Is the drive powered with a dedicated power supply? Is it USB 3.0 compatible, and if so, is it plugged into a USB 3.0 port?

losangeleskingsfan15 · August 23, 2021, 2:25am

It's a WD 3tb Green Drive Internal plugged straight into SATA. I pulled it from an older PC.

Macnbaish · August 23, 2021, 2:45am

Oh. Well then. I guess I’d see if you can run diagnostics on it somehow and try to verify drivers perhaps. I’m more of a Windows guy so I’m afraid I’m not a lot of help in that area.

racameron · August 23, 2021, 2:45am

The Green drives suffer because they are generally underpowered. For regular desktop use, you won't notice a real difference. But in a DVR you are using your drives with sustained reads/writes, which puts MUCH more stress on the drive.

For a DVR drive, you're better off getting a DVR/surveillance rated drive, preferably a CMR drive.

losangeleskingsfan15 · August 23, 2021, 4:12am

I see. Would a NAS drive suit for a DVR as well? Those are meant to run 24/7, right?

racameron · August 23, 2021, 4:23am

Not really. Several NAS drives are SMR, including the previously lauded WD Red drives. The only WD drives that match this type of environment are Red Plus or Purple.

In general, NAS drives are OK. If you want certainty, then you need to go higher end. In reality, any else will be better than what you have. The WD Green drives—and followed by Blue—are the bottom of the barrel; you can only go up from there.

losangeleskingsfan15 · August 23, 2021, 7:37pm

I heard about staying away from the Red drives. I read that surveillance hard drives have really slow read speeds, won't that interrupt recording playback?

chDVRuser · August 23, 2021, 7:50pm

I'm currently using these in my Synology NAS's running Channels DVR and they're CMR
WD40EFRX 4TB
WD100EFAX 10TB
WD101EFAX 10TB

What I remember is if model ends in EFAX and is smaller than 8TB, it's SMR.
WD Lists the following models as SMR vs CMR

SOURCES: https://www.anandtech.com/show/15878/western-digital-cleans-up-the-red-smr-nas-hdd-mess Who sourced it from https://blog.westerndigital.com/wd-red-nas-drives/

muzicman0 · August 25, 2021, 12:54am

Last I knew (admittedly, a long time ago), the green drives were bad in linux PC's because of the Idle park settings (or something like that). Basically, it caused excessive wear and tear on a green drive.

With that said, I use WD Red (not the pro) drives in my NAS (10 TB, and 6 TB), and have had no issues.

racameron · August 25, 2021, 1:36am

If you use Red drives for standard NAS purposes, then the SMR/CMR issue won't affect you. And if your drives are older than a few years, they're probably CMR so the discrepancy doesn't affect you.

hiperwall · August 25, 2021, 1:56am

Thanks. I use them for playback, but not for recording. I do have some that are only a year or so old.

racameron · August 25, 2021, 2:08am

If they're that new, then chances are they're SMR, and not well suited to continuous recording.

muzicman0 · August 25, 2021, 3:14pm

Turns out my 10 TB are actually Seagate (totally forgot that!), and they are CMR. The 6 TB (WD Red) are SMR, but I don't record directly to any of my NAS drives, so it should be no issue from what I understand.

losangeleskingsfan15 · August 26, 2021, 3:47am

So i ended up replacing my WD Green with a Seagate Ironwolf. What a day and night difference! The load never goes above 4 anymore. Thanks everyone for the help!