You flash CWM, but after reboot, you see the stock Android recovery.

: Select "install zip from sdcard" to choose your custom firmware files. Legacy Considerations for 2021 and Beyond How to Root + load CWM on Galaxy S2 ICS (AT&T and Rogers)

Look for a file like cwm-6.0.4.5-i9100.tar.md5 . Do use a ZIP file in Odin – Odin requires .tar or .tar.md5 .

Use this if you have stock recovery or cannot boot into system.

Your internal storage partition is corrupted or using the wrong filesystem.