FAS3220HA with 1 or 2 DS2246 shelfs + Flash pool

[Alfs29]

Hello everyone,

This is my small home/office system. I got it from ghetto shop (aka ebay), so i don't have Netapp support to ask questions.

I have FAS3220HA with 8.1.4 7-mode and 1 ds2246 shelf with 24x600gb sas, 4x 400GD SSD. Also i have some spare ds14mk shelfs with FC drives.

I could get one more ds2246 shelf and more SAS drives if needed for superconfig 😄

What would be recommended config for drives/shelfs?

1) Is it ok, to mix SAS and FC shelves? (i could uses FC shelf for both root volumes) Is this idea normal? What is bad with this idea it is fact that i can have only single link to fc shelf because on controller i use other FC pair (1 from each controller) for data.

2) Is 4 SSDs enough to make flash pool in ds2246 with 4ssd+20sas? Or is it better to have 5ssd and then have 2data+2par+1hs (ssd) (yes, i remember that 8.1 can have only 500gb for flash pool, but i could upgrade to 8.2 with 1.5TB flash pool size) + 16data+2par+1hs (sas)

Holy war raid-4 vs raid-dp?

3) Maybe its better to have 1 root + data + flashpool on ds2246 and other root + slower data on FC shelf? On the other hand i will loose SAS spindles that will be used for root aggregate 😕

In general, what would be community recommendations on how to setup drives?

Thanks

Aldis 

[kahuna]

do not put a Flash Pool on such a small system. FP is a CPU hog. In such configuration, CPU will become the bottleneck way before you hit the disks limit

[Alfs29]

Netapp KB doesn't say anything about huge CPU load 😕 yes it says that you will have "some" load on cpu but nothing like "beware of bad and evil cpu killer"

From my 10K SAS spindles i could get ~120IOPS/drive -> ~2100IOPs MAX when using 18 data drive group + 2dp . (3 root volume dp + HS)

I dont think that FAS3220 is only capable of this ammount.

Is it acceptable practice to have ssd's for flash pool in another shelf than data drives?

[kahuna]

Flash Pool is a great solution and if used properly can save you from going to hard disks quite a lot, and by extension, give much lower latency. However, the background operation is quite demanding.

the SSD disks can be in another shelf, just make sure you don't overload the stack

[Alfs29]

What about my other questions and considerations?

Is it ok, to have root aggr on another shelf (FC) with only single link?

Maybe have one root vol on ds2246 other on ds14mk? Maybe both on FC shelf?