IMU2 higher vibrations than IMU1 and 3, log help

Hi,

I am building a new hexacopter and on the maiden flight the copter altitude hold and compass were bad,
I figured that the alt problem might be from bad sonar setup and from setting
EK2_ALT_SOURCE = 1
Now I set it to 0 and set
RNG_USE_HGT = 50 and fixed my sonar scaling mishap,
RNGFND_SCALING = 2.03 to 1.53

I also changed primary compass to external as the internal one had a lot of interference

After looking more through the logs, specifically vibrations and such I noticed that IMU2 has significantly higher vibrations. I was under the impression that IMU2 and 3 were the vibration isolated ones while 1 was not, yet IMU1 and 3 perform better.

My log bitmask was default so for the next flight I set it to 655358 which should be to log all at full speed, so I can do FFT.

If someone has time could you look at the log, I know the vibrations are quite high and I think I fixed the altitude and compass problem, but IMU2 I just don’t know what to do with it.

Is there a way to disable IMU2? I am guessing EK2_IMU_MASK = 2 (0+2)?
Should I do a motor/compass calibration?
How do others deal with vibrations from a large hexacopter?

Specs:
Tarot X6 frame,
T-Motor MN5212
T-Motor 18x6.1 carbon propellers
Xrotor xheli 40A
Pixhawk 2.1
2x16Ah 6S

This is the log

Number 1 and 3 are super good Invensense sensors, number 2 is an ST sensor

Used together they give excellent immunity to most things that get thrown at them.

Don’t over think your way into a problem… 1 and two are isolated

Thank you, one other question

should INS_USE3 be 1? or what is it used for, if you know

you should be on a chibios firmware, and it should be 7