FE %Busy and FE port %Utilization

Question

I was looking at % Busy metric of FE director and Utilization metric of FE port. The %Busy of FE director is very high sometimes even though the FE port utilization is less, they do not relate each other. (I am using only one port, the other port is empty)

% Busy of FE director shows the percent of time director is busy.

Port 0 Utilization is about the calculation of port busy. How is this calculated? Why is the difference in percentages between two?

I know that I need to look at the director utilization and keep it under control for better performance, what does actually Utilization of port signify?

Thanks,

Amita2 · Accepted Answer

Hi,

Utilization is I/O per second to the benchmarked maximum. The maximum value used in the calculation is adjusted for the type and speed of the director.

But in newer arrays (Microcode:5773+), the utilization is measured on clock ticks where it actually calculates the count busy and count idle. These are not directly related to I/O's per sec.
If there are more Idle tick then its under-utilized and if more busy ticks its over utilized.

%busy would account only I/O per second.

Thanks

Amita Wasson

sracharla · Answer

Thanks Amita, that was helpful. From my obervations it seems like most of the performance issues are due to high %busy (IOPS) not due to utilzation.

I would like to add something to it from my obervation in SPA

there are two metircs %busy and % busy port 0/1 in SPA diagnostic views.

%busy would account only I/O per second. - this is correct when you look for the director as a whole.

when you look at the %busy port 0/1 - it is showing the utilization of port 0/1 (as per your clock ticks definition above).

And we also have another metric utilzation (when you double click the director), this is same as the %busy port 0/1 above.

Thanks

VMAX

FE %Busy and FE port %Utilization

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