We give a complete determination of the exact optimal worst-case repair bandwidth and repair I/O for linear exact repair of $(n,n-2,2)$ MDS array codes over every finite field $\mathbb{F}_q$ and for every admissible code length $3\le n\le q^2+1$. For repair bandwidth, we prove that the optimum is governed, up to a short explicit list of small exceptional cases, by the maximum of the sharpened $n$-only lower bound $\lceil(5n-8)/4\rceil$ and the projective counting, equivalently incidence-multiplicity, bound $2n-q-3$. For repair I/O, we obtain the analogous exact formula with $\lceil(4n-6)/3\rceil$ in place of $\lceil(5n-8)/4\rceil$, with the single special value at $n=4$. Thus, we completely resolve the first non-trivial redundancy and sub-packetization regime $(r,\ell)=(2,2)$ for both repair bandwidth and repair I/O.

翻译：本文完整确定了任意有限域$\mathbb{F}_q$上$(n,n-2,2)$ MDS阵列码在任意容许码长$3\le n\le q^2+1$下的精确最坏情况最优修复带宽与修复I/O。对于修复带宽，我们证明最优值由锐化的仅含$n$的下界$\lceil(5n-8)/4\rceil$与射影计数（等价于关联重数）界$2n-q-3$的最大值决定（除少量显式列出的特例外）。对于修复I/O，我们获得类似精确公式，其中以$\lceil(4n-6)/3\rceil$替代$\lceil(5n-8)/4\rceil$，仅在$n=4$处存在单一特殊值。由此，我们完整解决了修复带宽与修复I/O在首个非平凡冗余与子分组范围$(r,\ell)=(2,2)$下的问题。