Will mixing disk RPM's in aggr / loop / shelf / rg degrade performance?

BAMSKELIAN · ‎2012-02-20

My question is as follows, and I've only been able to find part of the answer. This is related specifically to performance and mixing, for the sake of discussion, 10k fc & 15k fc disks.

Will mixing 10k & 15k rpm disks in an AGGREGATE degrade performance of that aggregate to the 10k rpm disks? **YES** This is the only one I've been able to verify

Documented: http://media.netapp.com/documents/tr-3437.pdf page 15, under "Drive Speed"

Will mixing 10k & 15k rpm disks in a SHELF degrade performance of that SHELF to the 10k rpm disks?

Will mixing 10k & 15k rpm disks in a RAID GROUP degrade performance of that RAID GROUP to the 10k rpm disks?

Will mixing 10k & 15k rpm disks in a FC LOOP degrade performance of that LOOP to the 10k rpm disks?

Thanks for any assistance, or links to relevant documentation

_-Bamskel

BAMSKELIAN · ‎2012-02-21

Found the answer, not documented anywhere but from a Netapp guru friend.

SHELF performance: YES, it will degrade the FiberChannel LOOP connectivity to 2gb, disallowing it the 4g/8g connection found in dsmk4/esh4 shelves. It will NOT degrade the IOPS performance of the 15k disks on the shelf, if they are within a different aggregate.

RAID GROUP: Yes, it will degrade the IOPS performance of the Aggregate as a whole if there are 10k rpm disks in the Raid Group

FC LOOP: It will not degrade the performance of the loop to 2gb connectivity, disallowing it the 4g/8g connection found in dsmk4/esh4 shelves. Guru's actual words "It will make it to where the loop speed can only be 2G instead of 4G multipath. The only way to achieve a 4Gb/8Gb multipath is with a DS14MK4 shelf, ESH4 modules and 15K disks…otherwise it is a 2Gb/4Gb multipath loop."

aborzenkov · ‎2012-02-21

There is no 8Gb/s shelves available from NetApp.

bsti · ‎2012-02-21

Here are some additional details:

Mixing disk speeds within an aggregate or raid group: (possible, but as stated above not recommended)

https://now.netapp.com/NOW/knowledge/docs/ontap/rel802/pdfs/ontap/smg.pdf

Mixing disks in the same shelf (Not possible or at the very least highly not recommended)

Mixing disk shelves of differnt disk speeds in the same stack (Possible without performance penalty with DS4243 shelves, not with FC shelves)

https://now.netapp.com/NOW/knowledge/docs/hardware/filer/215-05825_A0.pdf

phamq · ‎2015-04-14

I know its an old topic but I have similar question.

By how much of a performance degradation occurs when adding 10k drives that are the same size as the 15k drives?