How to cut holes throughout the curved surface of a cylinder?
The following assumes you've already created a hollow cylinder.
Create the tangent plane where the cylindrical outer face is the first reference and the perpendicular plane is the second reference.
Create a sketch on this new plane and dimension a circle per your specifications.
For a cut specified to extend through the entire feature, click the drop-down menu and select "Through all". Click the green check to create the cut.
NOTE: For a blind-depth cut in a hollow cylinder, ensure the cut depth is significantly greater than the wall thickness. Otherwise, you will receive an error message about a section of the model with zero-thickness. This is due to a square cut on a round surface. The feature will not be created.
For a cut that extends through the entire feature, a full 360 deg pattern will repeat cuts. You need only specify the angle of pattern through half of the number of cuts you actually wish to be made. For this particular pattern, you may specify an angle of 150 deg and the number of instances of 6. However, it will work if you leave it the same as the solid cylinder. Click the green check to create the pattern.
Hollow cylinder with circular patterned cut.