Which statement best describes journaling and data integrity features among ext4, NTFS, and ZFS?

• A. ext4 uses journaling; NTFS uses metadata journaling with ACLs and encryption; ZFS uses copy-on-write with checksums, snapshots, pooled storage.
• B. ext4 uses journaling; NTFS uses metadata journaling without encryption; ZFS uses single-write semantics with no checksums.
• C. ext4 uses no journaling; NTFS uses journaling; ZFS uses copy-on-write with checksums, snapshots.
• D. ext4 uses journaling only for metadata; NTFS uses block-level checksums; ZFS uses extending file blocks only.

Answer: (A)

Journaling and data integrity features across different file systems vary in how they protect metadata and data, and what additional mechanisms they provide for reliability. Ext4 relies on journaling to keep filesystem metadata consistent after crashes; by default it journals metadata and can be configured to journal data as well, which helps recover from unexpected shutdowns without incomplete metadata. This makes it a robust, crash‑resistant option, though it isn’t designed around copy‑on‑write for all data.

NTFS also uses a journal, focusing on metadata integrity. In addition, it supports security features like ACLs and file encryption (via EFS), so the combination of metadata journaling with these security capabilities is accurate.

ZFS takes a different approach with copy‑on‑write at its core, meaning changes create new blocks rather than overwriting in place. It also provides checksums for both data and metadata to detect corruption, supports snapshots for point‑in‑time copies, and uses pooled storage via zpools to manage space. This combination—copy‑on‑write, checksums, snapshots, and pooling—is what sets ZFS apart.

The other statements are off because ext4 does use journaling, not “no journaling”; NTFS does include encryption capabilities, so saying it has no encryption isn’t accurate; and ZFS is not single‑write and it does use checksums, contrary to those descriptions.