Currently running a 2 drive array, 1 drive is parity. Will adding a 2nd data disk improve read performance?

[geekjitsu]

I've searched the forums and google and can only seem to find that faster drives will improve performance, but no mention if additional drives improve performance.

 

Current set up is:

1 x 1TB NVME as cache

2 x 12TB WD Red 5400rpm drives.  1 is parity, 1 is data.

 

I plan to get 2 more 12TB WD Reds when they go back on sale, so for now this is a POC for moving from Synology to Unraid.

 

I'm moving data (movies and pictures) over from my Synology DS412+ that was configured in a RAID5.  Write performance to the Unraid is great (as expected), but after the data is moved from cache to the array accessing it is painfully slow.

 

Will adding those 2 additional WD Reds improve performance?  I think the answer is "no" because data is not striped across the disks and that the only way to improve read performance would be to move to faster drives.

 

Thanks in advance.

[JorgeB]

1 minute ago, geekjitsu said:

I think the answer is "no" because data is not striped across the disks and that the only way to improve read performance would be to move to faster drives.

Correct, though it could be faster if for your use case you can read files from different devices simultaneously.

[trurl]

6 minutes ago, geekjitsu said:

Write performance to the Unraid is great (as expected)

1 parity 1 data is a special case 

[trurl]

For more on the general case (or maybe 2 general cases) of writing parity, see here:

 

 

[Mihle]

What do you mean by "Painfully slow"?

Is it slow to copy from it to a computer for example? If so, what is the speed you are getting?