I figured this would be a commonly asked question, tried Googling and searching here, probably using the wrong terms.

 

Basically I'm looking to add a few more TB to my array. I'm eligible for Western Digital's education discount so I was checking, they've got 4TB Reds for $100, not a bad deal. Currently I'm running 3x 4TB HGST Deskstar NAS (one for parity) which are 7200rpm drives, while the WD Reds are 5400rpm from what I've read. I run most things off my cache drive (512GB SSD), but I do stream some fairly high bitrate (4k stuff) from Plex. Currently seek times are close to instant even on 4k videos, but I'm concerned dropping down to the 5400RPM Reds may hurt performance for the items stored on those drives.

 

Are the WD Reds going to hurt performance (especially from my Plex docker) when data is coming from them?

 

The HGST NAS drives cost about 50% more at $160, but match the speed I currently have. Always looking to save money though when I can, but not with a significant performance decrease.

 

I'd appreciate any advice! Thanks!

Edited March 3, 20179 yr by bnr32jason

I can't answer your question directly but I used a program called Lan Speed Test from Totusoft (Google for it) to test the transfer to and from my Media server.  (Spec's below.)  None on the drives in this server are 7200rpm drives.  I ran the test using a 9GB file.  Transfer speed to the server was 88,450,879 Bytes per second and download speed was 99,547,989 Bytes per second.  (I use the 'Reconstruct write' method on my servers so I don't need a cache drive for upload speed.)

Edited March 3, 20179 yr by Frank1940

Biggest thing keep your faster drives for parity otherwise I don't think you'll have a problem unless you have a network bottleneck.

1 hour ago, phbigred said:

Biggest thing keep your faster drives for parity otherwise I don't think you'll have a problem unless you have a network bottleneck.

This only makes sense if your biggest concern is making sure slow parity doesn't degrade write performance. Parity isn't used when reading (except when the disk to be read is disabled).

 

In the case of media collections, where files are often written once but read many times, write speed isn't that important. I don't even bother caching most of my shares.

And if you do cache writes, all the more reason to not be concerned with parity speed.

6 hours ago, trurl said:

And if you do cache writes, all the more reason to not be concerned with parity speed.

I was thinking for parity check speeds as that's a write intensive process, slower the drive the longer the checks take. I've tested this with a 7200 and 5900 drive. Difference of close to an hour. 

Edited March 4, 20179 yr by phbigred
Reviewed my parity check history for times.

13 hours ago, bnr32jason said:

Are the WD Reds going to hurt performance (especially from my Plex docker) when data is coming from them?

 

No impact at all with Plex streaming => the WD Reds can easily stream fast enough to saturate a Gb network -- so there's NO advantage in using faster drives.

 

The only performance difference you'll notice is that parity checks will, as noted above, take longer, since they can only run at the speed of the slowest drive involved in the check -- so even a single 5400rpm drive will slow down the checks (assuming equal platter density, which is true for the 2 drives you noted).

 

Note:  If you'd prefer to just get more of the HGST drives, Newegg has them for $139.99 through tomorrow.  ($149.99 minus a $10 Promo code)

https://www.newegg.com/Product/Product.aspx?Item=9SIA2W04177421&cm_re=HGST_4TB_NAS-_-22-145-912-_-Product

By the way, $100 is a VERY good price for a 4TB Red.    Do you have a link to that offer ??
 

21 hours ago, bnr32jason said:

I'm eligible for Western Digital's education discount so I was checking, they've got 4TB Reds for $100

 

8 hours ago, garycase said:

By the way, $100 is a VERY good price for a 4TB Red.    Do you have a link to that offer ??