PAR2 operation consumes ALL I/O Disk

[seanvree81]

Running Sabnzbd 1.2.0 as a service on Windows10E

So, I've been having an issue when SAB is extracting files, it brings any otbher processes that are using the I/O BUS almost to a halt. A lot of things stop working while it's unpacking. I can watch the system monitor and PAR2 process uses 100 of the disk. It looks like it's using the 64x version of Par2. Itwill finish just fine, but a lot of other stuff stops working. The memory/Process and network resources are all fine.

My intermediate drive that SAB is using is a WD 7200RPM 3TB drive.
Processor: Intel i7 6700K
Memory: 32GB
My settings are as follows:

Download all PAR2 Files: OFF
Enable Quick check: ON
Enable MuliCore PAR2: ON
No params set.
Post-Process only verified jobs: OFF

So, should I turn off MultiCore PAR2?

What do you suggest?

Thanks,

[safihre]

Try indeed without Multicore!

[sander]

So, I've been having an issue when SAB is extracting files, it brings any otbher processes that are using the I/O BUS almost to a halt.

On an i7, with 32GB ... ?! I reall wonder wether non-multicore will solve that.

Just checking: you're not using a NAS/networkdrive as (final) storage, are you?

[seanvree81]

So, I've been having an issue when SAB is extracting files, it brings any otbher processes that are using the I/O BUS almost to a halt.

On an i7, with 32GB ... ?! I reall wonder wether non-multicore will solve that.

Just checking: you're not using a NAS/networkdrive as (final) storage, are you?

That's what I was thinking.

Nope, internal SATA WD drive.

[safihre]

Par2multicore will use all the cores it can get, it will use all.

This also means that if you have for example 4 cores, there will be 4 cores reading from disk.
Or when you have 8 cores (or threads) it will have 8 threads reading from disk. This is probably what is causing the strain on the disk.

You can use the "-t0" switch:
https://sabnzbd.org/wiki/configuration/ ... multi-core
"-t0 Use multi-core for repairs but not for verify (prevents disk trashing)"

[seanvree81]

Par2multicore will use all the cores it can get, it will use all.

This also means that if you have for example 4 cores, there will be 4 cores reading from disk.
Or when you have 8 cores (or threads) it will have 8 threads reading from disk. This is probably what is causing the strain on the disk.

You can use the "-t0" switch:
https://sabnzbd.org/wiki/configuration/ ... multi-core
"-t0 Use multi-core for repairs but not for verify (prevents disk trashing)"

Yeah, roger that. I've done some testing and you're right.


So, if I move my "download" folder to my system SSD, I should, in theory, be able to re-enable multi-core, right?

[safihre]

Yes

[seanvree81]

Par2multicore will use all the cores it can get, it will use all.

This also means that if you have for example 4 cores, there will be 4 cores reading from disk.
Or when you have 8 cores (or threads) it will have 8 threads reading from disk. This is probably what is causing the strain on the disk.

You can use the "-t0" switch:
https://sabnzbd.org/wiki/configuration/ ... multi-core
"-t0 Use multi-core for repairs but not for verify (prevents disk trashing)"

Hey @safihre ,

Hate to bring this up again, but I'm starting to have this issue again, not sure why it started again.

Just to confirm as I look at the settings (as they may have updated when we last posted).

If use the switch - "-t0" for PAR2, does that mean that I need to have part2_multicore enabled in "special"?

Thanks,

[safihre]

You are on 2.1.0, right? Here things changed.
Make sure you have in Config > Switches, Multipar Enabled.
Then set for Extra par2 parameters: "/lc1"
This will only use 1 thread, limiting disk activity.
https://sabnzbd.org/wiki/configuration/ ... e-multipar

Unfortunately MultiPar doesn't let you specify number of threads separate for Verify/Repair, but it's so much faster than the old version that probably your repairs will still be fast.

[seanvree81]

You are on 2.1.0, right? Here things changed.
Make sure you have in Config > Switches, Multipar Enabled.
Then set for Extra par2 parameters: "/lc1"
This will only use 1 thread, limiting disk activity.
https://sabnzbd.org/wiki/configuration/ ... e-multipar

Unfortunately MultiPar doesn't let you specify number of threads separate for Verify/Repair, but it's so much faster than the old version that probably your repairs will still be fast.

Yes, I'm on 2.1

Okay, understood, a couple of follow up questions:

If I'm using a Samsung SSD 1TB to write to during extraction and verification, I should be able to bump up PAR2 params to /lc12 or /lc13, without it totally maxing out the disk I/O, right?

Also, should I leave par2_mulicore disabled (unchecked) in SPECIAL settings?

[safihre]

The par2_multicore parameter does not affect Multipar and will be removed in the next SABnzbd version (2.2.0).

I am surprised you are having any issues at all with a 1GB SSD, my 512GB SSD does pretty well with Multipar. Maybe virusscanner? I have excluded the temporary directory from virus-scans.
So I would expect /lc12 to work well.

[seanvree81]

The par2_multicore parameter does not affect Multipar and will be removed in the next SABnzbd version (2.2.0).

I am surprised you are having any issues at all with a 1GB SSD, my 512GB SSD does pretty well with Multipar. Maybe virusscanner? I have excluded the temporary directory from virus-scans.
So I would expect /lc12 to work well.

Cool, I'll test it out and see how she works!

Thanks!

[seanvree81]

Hey @Safihre,

okay, so did some testing, and I can't figure this out.

For some reason, when it's "checking" it using about 75% of the total SSD drive's resources

When it's extracting, it uses 100% and it DOES complete, but the entire system is almost non-responsive until it completes.

See my Screenshots. Does this make sense to you?

Sab Config:



System idle / Sab DLing:



System Checking:



Extracting:

[safihre]

Aah I see.. You have very big downloads.. That indeed requires really large amounts of data since it really has to check the whole 40GB.
Have you tried the /lc1 switch?

[seanvree81]

Aah I see.. You have very big downloads.. That indeed requires really large amounts of data since it really has to check the whole 40GB.
Have you tried the /lc1 switch?

I'll test and get back to you.