6. Given the equation of an ellipse is $\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1(a>b>0)$, the left vertex is $A$, the left and right foci are $F_{1}$ and $F_{2}$, and $D$ is a vertex on the minor axis. If $3 \overrightarrow{D F_{1}}=\overrightarrow{D A}+2 \overrightarrow{D F_{2}}$, then the eccentricity of the ellipse is ( ).
(A) $\frac{1}{2}$
(B) $\frac{1}{3}$
(C) $\frac{1}{4}$
(D) $\frac{1}{5}$
6. D.

Notice that, $D(0, b), A(-a, 0)$, $F_{1}(-c, 0), F_{2}(c, 0)$.
Then $3(-c,-b)=(-a,-b)+2(c,-b)$ $\Rightarrow-3 c=-a+2 c \Rightarrow \frac{c}{a}=\frac{1}{5}$.