Here is an very instructive moment from the game @Deranged - @FelixRC.
In the following position after Re7, black's plan is to play Kc7 and d6 to develop his bishop on c8, white wants to keep control of the b6- and the d6- squares to keep black's position blockaded. @Deranged played Rd6 with the idea of Rhd1 next, and it looks absolutely correct: White secures the b6- and the d6- squares and double the rooks on the d-files at the same time.
However, the while all of this looks nice, after 17...Kc7 18.Rhd1 black has the move 18...Ne8! Taking advantage that the d6-rooks is exposed to black's king, 19.Nd5 is not possible and as white is forced to retreat with his rook, and as his b6-knight is under attack, forced to trade the knight for black's bishop. After 19.Nxc8 Rxc8 20.Rd5 d6, black's position has vastly improved. (In the game black played 17...Nh5? and quickly lost the knight and the game in a few moves)
The correct move for white after 16...Re7 is 17.a4!, intending to defend the white knight on b6 is a4-a5, black has two choices:
1) Prevent a4-a5. This, however, results in a new weakness on a5 and costs time, which white can exploit by 18. Ba2! Kc7 19.Nc4! (heading for d6) Ne8 20.Ne3! (the threat of Nd5+ and Nf5 forces the win of material; 20.Nxa5?! Ra8 is weaker) Nf6 21.Nf5 Re8 22.Nd6! (final destination, 22.Ng7?! gives black counterplay after ...Rg8) Rf8 23.Bxf7+- white wins a pawn while still retaining the blockade.
2) Allow a4-a5 and play Kc7 followed by d7-d6. Black tries to develop his pieces as quickly as possible, but white's b6-knight also prove to be very strong: 17...Kc7 18.a5 d6 19.Rd3! Be6 20.Rhd1 Ne8 (20...Rbd8 [Our daily puzzle #8!] 21.Bb3! Bxb3 22.Rc3+ Kb8 23.Rxd6!, winning a pawn since 23...Rxd6?? leads to mate: 24.Rc8+ Ka7 25.Ra8#) 21.b4 Rd8 22.Kb2 and although black prevented the immediate loss of material, white's blockade has only strengthened and white will eventually breakthrough either by c2-c4-c5, opening the d-file, or at a specific time, c4 and b5 and bxa6 to penetrate on the b-file (most likely after moving the knight away from b6).
These variations are very complex but they illustrate 2 important concepts: It's best to control holes with pawns and pieces and it can be useful to give up a hole in exchange of another.
Here is an very instructive moment from the game @Deranged - @FelixRC.
In the following position after Re7, black's plan is to play Kc7 and d6 to develop his bishop on c8, white wants to keep control of the b6- and the d6- squares to keep black's position blockaded. @Deranged played Rd6 with the idea of Rhd1 next, and it looks absolutely correct: White secures the b6- and the d6- squares and double the rooks on the d-files at the same time.
However, the while all of this looks nice, after 17...Kc7 18.Rhd1 black has the move 18...Ne8! Taking advantage that the d6-rooks is exposed to black's king, 19.Nd5 is not possible and as white is forced to retreat with his rook, and as his b6-knight is under attack, forced to trade the knight for black's bishop. After 19.Nxc8 Rxc8 20.Rd5 d6, black's position has vastly improved. (In the game black played 17...Nh5? and quickly lost the knight and the game in a few moves)
The correct move for white after 16...Re7 is 17.a4!, intending to defend the white knight on b6 is a4-a5, black has two choices:
1) Prevent a4-a5. This, however, results in a new weakness on a5 and costs time, which white can exploit by 18. Ba2! Kc7 19.Nc4! (heading for d6) Ne8 20.Ne3! (the threat of Nd5+ and Nf5 forces the win of material; 20.Nxa5?! Ra8 is weaker) Nf6 21.Nf5 Re8 22.Nd6! (final destination, 22.Ng7?! gives black counterplay after ...Rg8) Rf8 23.Bxf7+- white wins a pawn while still retaining the blockade.
2) Allow a4-a5 and play Kc7 followed by d7-d6. Black tries to develop his pieces as quickly as possible, but white's b6-knight also prove to be very strong: 17...Kc7 18.a5 d6 19.Rd3! Be6 20.Rhd1 Ne8 (20...Rbd8 [Our daily puzzle #8!] 21.Bb3! Bxb3 22.Rc3+ Kb8 23.Rxd6!, winning a pawn since 23...Rxd6?? leads to mate: 24.Rc8+ Ka7 25.Ra8#) 21.b4 Rd8 22.Kb2 and although black prevented the immediate loss of material, white's blockade has only strengthened and white will eventually breakthrough either by c2-c4-c5, opening the d-file, or at a specific time, c4 and b5 and bxa6 to penetrate on the b-file (most likely after moving the knight away from b6).
These variations are very complex but they illustrate 2 important concepts: It's best to control holes with pawns and pieces and it can be useful to give up a hole in exchange of another.