Is there any Cache setting that needs to be checked while configuring IRIS Community Edition 2025.2 in Linux and does it impact WIJ recovery.

The following points are relevant to your questions:

1. Cache/WIJ Settings and WIJ Recovery:
   InterSystems IRIS automatically checks the Write Image Journal (WIJ) file during startup to determine if recovery is needed. Abnormal shutdown conditions can cause databases to enter recovery if the WIJ indicates pending updates. The WIJ recovery process ensures data integrity by restoring or comparing blocks depending on when the crash occurred during the write protocol phases 12.

   You can adjust the WIJ directory and set a target size for the WIJ. Modifying these settings is possible via the Management Portal under System Administration > Configuration > System Configuration > Journal Settings. Restarting InterSystems IRIS is required only for clustered instances and not standalone instances. Additionally, entering a non-zero target size for the WIJ reserves space on the storage device, which can improve stability 34.

2. Database, WIJ, and Journal Settings:
   Placing the database, WIJ, and journal files in the same snapshot group might impact performance and recovery. Keeping these files together risks consistency due to snapshot delays or concurrent operations. Splitting these onto separate groups is often recommended for optimized recovery and performance 43.

3. WIJ Mismatch Errors:
   A mismatch error with the WIJ could originate from improper write completions before crashes. Using the same snapshot group might exacerbate such issues due to delayed writes or inconsistencies in file updates during snapshots. Adjusting configurations as recommended above could mitigate these errors 23.

Based on this, consider separating WIJ and journal files from the database storage to reduce the risk of mismatch errors and improve recovery outcomes. 1234

Sources:

WIJ Block Comparison^DOC

If you encounter MISMATCH.WIJ, contact InterSystems Worldwide Response Center (WRC) before proceeding.

Note: If a database is to be restored following a crash, ensure that prior to the restore you start the instance without WIJ and journal recovery (see Starting InterSystems IRIS Without Automatic WIJ and Journal Recovery). This avoids both creating discrepancies that will be detected by the WIJ comparison and incorrectly applying WIJ blocks or journal data (see Journaling) to a version of a database for which they were not intended.

Some storage subsystems, particularly local drives on laptops and workstations, use an unsafe form of write-back caching that is not backed by battery or by non-volatile memory. This defeats the two-phase write protocol that InterSystems IRIS performs and can lead to corruption following a hardware crash or power loss that is detected during WIJ compare.