About lob

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🔍 How Unsecured & Uncompressed LOBs Degrade Backup Performance

1. Storage as BasicFiles (vs. SecureFiles)

BasicFiles LOBs are the legacy storage method in Oracle.

They lack features like compression, deduplication, and efficient I/O.

Reading BasicFiles during backups involves more disk I/O, as data is stored in a less optimized manner.

2. No Compression = Larger Backup Volume

Uncompressed LOBs consume more space on disk.

During backup, especially RMAN or CommVault, this means:

More data needs to be read, transferred, and written to backup media.

Increases network load and backup window duration.

3. Streaming Performance Bottlenecks

LOBs often bypass RMAN’s optimized data streaming methods.

For very large LOBs, this creates slow, row-by-row or block-by-block reads.

4. Inefficient Incremental Backups

Changes to a small part of a LOB can result in the entire LOB being flagged as changed.

This causes RMAN to back up the entire LOB again, even with block change tracking.

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✅ Why SecureFiles with Compression Help

SecureFiles LOBs support:

Compression (medium/high)

Deduplication

Faster read/write access

This results in:

Smaller backup sizes

Less disk I/O

Faster overall backup performance

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📌 Summary

LOB Type Compression Impact on Backup Notes

BasicFile No ❌ Slowest Legacy, inefficient

BasicFile Yes ⚠️ Somewhat better Compression still limited

SecureFile No ✅ Faster Modern I/O improvements

SecureFile Yes ✅✅ Fastest Optimal for backup