The rotational latency is also somewhat negated as the platters are also smaller.

The decrease in physical size from 3.5  to 2.5 offsets some of the 15k to 10k difference.

There are lots of write-ups about  2.5 10k vs 3.5 10k drives.





Spelling errors courtesy of Swype for iOS...

Tim McCarthy, Consultant at Presidio
From: toasters-bounces@teaparty.net <toasters-bounces@teaparty.net> on behalf of Francis Kim <fkim@BERKCOM.com>
Sent: Monday, November 27, 2017 3:12:49 PM
To: John Adams
Cc: toasters@teaparty.net
Subject: Re: 3.5" 15KRPM -vs- 2.5" 10KRPM SAS
 
Shorter stroke is true enough but there’s no getting around the longer rotational latency, which determines the bulk of the HDD access time.

.

On Nov 27, 2017, at 9:07 PM, John Adams <intheyc@gmail.com> wrote:

Hello,
I have AGGRs made out of 3.5" 15KRPM SAS drives.  One of these drives failed, and NetApp sent a 2.5" 10KRPM SAS drive in a 3.5 sled as replacement.

After asking about this, they said:

After investigating, the following were my findings:


"As part of the NetApp qualification process, there is no performance degradation with the qualified X90-412B-R6 / SP-412B-R6 10K RPM drive as the seek distances are reduced to be equal to a full stroke 15K RPM drive."

As for the physical size difference:


"The only difference is that the 412A is a 3.5 inch HDD while the 412B is a 2.5 inch HDD. The difference in size is negated by a bracket within the carrier assembly in the 412B. So while the two HDD’s look different, the 412B is fully compatible with the 412A."


So what's your take on this?  The "don't mix 10K and 15K drives in the same aggr" keeps ringing away in my head.

Thanks for your thoughts.






_______________________________________________
Toasters mailing list
Toasters@teaparty.net
http://www.teaparty.net/mailman/listinfo/toasters