What to choose for connecting servers - SFP + or DAC?

Question

network hardware

Hello everybody.
Somehow I never went beyond RJ45, but now the question arose of upgrading 10 gigabit equipment. You can buy something like MikroTik Cloud Router Switch CRS326-24S+2Q+RM.
But then the question is - what to prefer?
You can connect the switch with a DAC cable to the SFP + ports of the server network cards, something like SNR-SFP + DA-1.
Or you can install something like Mikrotik SFP + 10G, 300m, DDM, LC duplex, 850nm (S + 85DLC03D) into the network ports and switch ports and connect everything with optics.
Which option is better?
Given that you need to drive data from and to server sas ssd from hypervisors to storage.

Answer 1

Within one rack - definitely DAC.
Optical patchcore has a number of problems -
degradation of optics
- attenuation at the joints, dust
- low resistance to physical damage
From personal experience with optics
on line. The problem was not immediately found.
2. Some bears in the server room very easily touch the optics, which at best leads to temporary interruptions, and at worst, the iSCSI cluster crumbles.
3. When replacing modules, some Neanderthals wipe the optical patch cord with their hands, sleeves, or even blow on it, which leads to attenuation and all the ensuing problems.

Answer 2

DAC cables are cheaper and NIC compatibility is wider than sfp modules

Answer 3

If everything is within one or two racks, then use ready-made compatible sfp + cables.
It will be cheaper and easier.