Currently my unRAID hast 4 WD Reds 4TB, 1 for parity and 3 for data. I use an 480 GB SSD as a cache drive.

 

I'd like to add 2 additional drives and I'm asking myself, should I stick with the WD Reds, as they are power efficient, silent and rated for 24/7 usage, or should I replace the parity drive with a faster drive and repurpose the WD Red parity drive as a data drive?

 

I assume the benefit of a faster parity drive is primarily faster write speeds (and parity rebuilt but that is a rare procedure). As most of my writes go through the SSD cache drive, I wonder, whether the increased power usage and probably more noise of a faster drive would be rectified by any noticeable speed improvement. The parity drive spins most of the time, while you access the server, and thus contributes most to the average power usage and noise.

 

Are there are any reasons, that I still could benefit from a faster parity drive even when using a SSD cache drive? And if so, what is the current recommendation for a fast parity drive? A WD Red Plus, a Seagate or a Hitachi?

 

Pete

... I assume the benefit of a faster parity drive is primarily faster write speeds (and parity rebuilt but that is a rare procedure). As most of my writes go through the SSD cache drive, I wonder, whether the increased power usage and probably more noise of a faster drive would be rectified by any noticeable speed improvement.

 

The write speeds won't be any faster unless you're doing multiple simultaneous writes -- and if all of those writes are cached it still won't make any difference.    It will have ZERO impact on a parity rebuild, since the rebuild is limited by the speed of the slowest drive involved in the process [same is true for parity checks].

 

 

... The parity drive spins most of the time, while you access the server, and thus contributes most to the average power usage and noise.

 

Not at all true.  The parity drive only spins when you're WRITING to the server ... it isn't accessed at all during reads [unless you have a failed disk which is being emulated by the system -- in which case ALL drives are being accessed to "read" that drive]

 

 

Bottom line:  I'd just stay with the WD Reds.