Turbo write

[JonathanM]

14 minutes ago, superloopy1 said:

Guys, do i set the number of drives to the max in my array prior to doing a parity check? Parity check takes an age on my system, just looking for ways to speed it up besides buying a whole new setup ;)>

Turbo write doesn't effect check speed.

[superloopy1]

19 minutes ago, JonathanM said:

Turbo write doesn't effect check speed.

No?

 

I've never understood this thread and i've read it back to back a number of times. So we are only talking write speeds that are affected by this, reads  are not handled similarly? Apolgies if i'm way off beam here .... educate me.

[Squid]

Yes, write speed when writing a file.  Reads are not affected at all and will happen at the native speed of the drive (subject to bandwidth considerations etc)

[Hoopster]

7 minutes ago, superloopy1 said:

I've never understood this thread and i've read it back to back a number of times. So we are only talking write speeds that are affected by this, reads  are not handled similarly? Apolgies if i'm way off beam here .... educate me.

Since unRAID stores a single file, regardless of size, on only one disk (no data striping across disks) read speed is limited by the speed of the disk on which the file is stored.  There is no way to speed this up.

[superloopy1]

Thanks guys, understood now. I'm stuck with an extremely slow parity check it appears, heyho ...

[JorgeB]

2 minutes ago, superloopy1 said:

Thanks guys, understood now. I'm stuck with an extremely slow parity check it appears, heyho ...

Start a new thread in the general support forum and include the diagnostics saved during a check.

[trurl]

59 minutes ago, superloopy1 said:

extremely slow parity check

How slow? 2-3 hours per TB of largest drive is typical

[itimpi]

19 hours ago, superloopy1 said:

Guys, do i set the number of drives to the max in my array prior to doing a parity check? Parity check takes an age on my system, just looking for ways to speed it up besides buying a whole new setup ;)>

There is no way to speed up the parity check simply by changing some settings as its speed is determined by the hardware capabilities of your system.  Normally the limiting factor is the speed of the slowest drive in the array, although it is also possible for the way the drives are connected to have a limiting effect.

 

You also want to ensure that no other disk accesses are being made to the array at the same time as in such a case both of them have their performance adversely affected.

 

If you have large drives then it may be worthwhile installing the Parity Check Tuning plugin to at least restrict the check to running outside prime time.

[Hexenhammer]

Guys, I don't understand something here, it says all drives will  spin up, is that assuming people have default share settings across all drives?

What if i isolate shares per drive until they filled up [so other hdds are in permanent OFF mode]

Will turbo write spin them up too, even if they empty and have no shares on them?

 

Thanks

[Kilrah]

Yes because parity doesn't know or care about shares or files, only about disk blocks.

In order to calculate parity for a given disk block when writing to one drive either you read existing parity and adjust it against the write, or you read the corresponding block from all disks and recalculate parity "from scratch".

The former is slow due to disk seeking time, which is why the other (turbo/reconstruct write) is an option.

Edited December 17, 2022 by Kilrah

[cprn]

If auto selects read/modify/write all the time, what is the point of having an auto option that does nothing?

[JonathanM]

1 minute ago, cprn said:

what is the point of having an auto option that does nothing?

Placeholder for future implementation.

[KptnKMan]

I've been considering turning this on for a while.

 

Just asking, is there a timeline or idea for when the auto option will be implemented?