#Performance in a mixed SATA and SAS stack?

1 messages · Page 1 of 1 (latest)

tight badge
#

If you can please help me out on following two questions below.
There are two stacks on FAS8200, one has 8 SAS shelves, and the other has 4 SAS shelves and plus 1 SATA shelf.

  1. Would the performance in all SAS shelves be better than mixed ones, and why?
  2. If we are adding 3 more SAS shelves, I guess, the only option we can have is to add them into that stack with 5 shelves due to 8 max limit. Correct?
fallow wave
#

What is the "type" of your Shelves ?

#

And if I remember the most slowly part of disk may be slow the other faster disk in the same shelf, it's like a traffic jam, even if you have a Ferrari, you cannot go faster than the car in front of you 🏎️

tight badge
#

DS224IOM6, the same shelves in this mixed stack for both SATA and SAS disks.
DS22412IOM12A, in the other stack for all SAS disks.
Understand your analogy, but, how could we apply here?

charred path
#

The limit is 10 shelves, but same thing - 8+3 > 10. Mixing them isn't a huge problem. There used to be concerns about having SAS and SATA on the same controller, but with ONTAP 9 and per aggr consistency points, that is mostly not a concern now

#

also you'll have a different type of shelf in there - there's no SATA DS224x drives

#

main thing in a single speed transition at most.. so 6-6-6-12 is ok, or 12-12-12-12-6.. but not 12-12-6-12-12 for example

tight badge
#

Those new shelves are DS224-12, so, if we are going to and we have to add them into DS224IOM6 stack, it is going to be 6-6-6-6-6-12-12-12. 6G should be slower than 12G, with mixed them together, I am still not clear why they are not a concern comparing to the other stack, they are all 12G.

torpid condor
#

are you out of sas ports to create a new stack?

tight badge
torpid condor
#

yeah, that's what it looks like.

tight badge
#

So, could the performance be different between these two stacks? so, it looks they used the same type of shelves "DS224IOM6" for SATA and SAS disks?

torpid condor
#

can you drop me the serial # of the system?

tight badge
#

How could I do that?

torpid condor
tight badge
#

something wrong...i couldn't do it. could you try it out again?

torpid condor
#

Thank ya. -
my 2 cents.
So outside of adding in additional SAS cards, stack 2 is probably the best e.g. new shelves with IDs 15,16,17,18.

sidenote: You can upgrade the IOM6 to IOM12, however the shelf has to be power-cycled for this.

Few other notes, it looks like you'll have to up the firmware on the shelves, they're showing 0200, and 0210 is required for mixed stacks.

§IOM12 modules require in-band ACP
§IOM6 ACP must be upgraded to ACP firmware 0210 or later first

tight badge
#

Right, we are going to add 3 new shelves onto the stack with 5 shelves.
So, the mixed SATA and SAS in the stack would be slower than all SAS stack, may be a bit?

torpid condor
#

at that level it's not really the disk. it's the IOM. it'll run the stack at 6.

tight badge
#

Got it. So how much difference between IOM6 and IOM12?

torpid condor
#

6Gbps

tight badge
#

Right, sounds quite some difference. I can upgrade IOM6 to IOM12 even with that SATA disks?

torpid condor
#

yup. but it's a hard down for the shelf.

#

would be easier to add in a SAS card.

#

and create a 3rd stack.

hearty dust
#

Honestly you won't notice a difference unless you have SSDs IMO.