Some of my HDDs failed. 2 drives to be exact.  Since those are old drives already, can we match new ones with different drive speeds and different brands? 

 

I understand that parity should be the biggest drive.

 

Which speed will be be best to use?  5400 rpm, 5900 rpm or 7200 rpm?

 

Thanks

Yes, you can mix and match drive sizes, speeds, and brands.

 

The only constraints are:

 

(a)  The parity drive must be >= any other drive in the array

(b)  If you're by any chance still using v4.7, then the largest drive supported is 2TB

 

There are two factors that heavily influence the transfer speed of your drives -- rotational rate and the areal density.  The modern 1TB/platter drives running at 5400 or 5900 will have far better sustained transfer speeds than less dense drives spinning at 7200rpm.    Obviously if two drives have the same density the one with the higher rotation rate will be faster.

 

But the 7200rpm drives also tend to use more power and run warmer than the more energy-efficient drives that are very popular.  Personally, I only use WD Reds or Seagate NAS units in my arrays -- they're excellent drives with 1TB platters and excellent performance.

 

garycase,

 

What do you consider Seagate NAS models?

garycase,

 

What do you consider Seagate NAS models?

 

http://www.seagate.com/internal-hard-drives/nas-drives/nas-hdd/?cmpid=ppc-_-nas-_-g-_-us-_-seagate%20nas%20drives-_-e

Personally, I only use WD Reds or Seagate NAS units in my arrays -- they're excellent drives with 1TB platters and excellent performance.

 

I second that - did a lot of research and have just started building my new unit with 3Tb WD Reds and they seem very good :-)

FWIW, here is a good article on hard drive failure rates from BackBlaze.

 

http://blog.backblaze.com/2014/01/21/what-hard-drive-should-i-buy/