CHFI Storage Forensics and File System Analysis Practice Question
During a forensic investigation, you encounter a RAID 5 array consisting of three 1 TB disks. The array is failed, and you need to reconstruct the original data. Which of the following approaches is MOST appropriate for data recovery?
⚠ Common exam trap
The CHFI exam often tests the misconception that a simple XOR of all disk images (Option C) is sufficient for RAID 5 recovery, but this fails because the parity is distributed and not a simple XOR of the entire disk; the correct approach requires knowing the RAID geometry and using a tool that handles stripe-level reconstruction.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use EnCase to perform a RAID rebuild with known parameters
EnCase Forensic has a built-in RAID reconstruction feature that can automatically rebuild a RAID 5 array from disk images when the RAID parameters (stripe size, parity rotation, disk order) are known or can be detected. This is the most appropriate approach for a failed RAID 5 array, as it handles the parity-based striping and reassembles the logical volume without requiring manual XOR operations or risking data corruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Mount each disk individually and copy files
Why it's wrong here
Mounting each disk individually treats every physical disk as a standalone filesystem, but RAID 5 stripes both data and parity across all member drives at the block level. The superblock and filesystem metadata are themselves striped, so a single disk contains only fragments of the logical volume and cannot be mounted as a coherent filesystem. At best, raw file carving might recover some files, but the standard forensic workflow of mounting to inspect the logical structure will fail without reconstructing the array.
- ✗
Run `mdadm --assemble --scan` on the images
Why it's wrong here
The `mdadm --assemble --scan` command only works on Linux software RAID (MD) devices whose superblock metadata is embedded in each member disk and identifies array UUID, disk roles, and state. In a hardware RAID 5 implementation, the controller stores configuration in its own nonvolatile memory or in a controller-specific metadata format (e.g., DDF or proprietary), not in Linux MD metadata. Even if the disks were from a Linux MD array, blindly running `--scan` on raw images may fail if the superblock offsets are altered or if the images are partial; in a forensic context, you must verify metadata manually rather than rely on auto-detection.
- ✗
Use `dd` to image each disk and then XOR the three images together
Why it's wrong here
Simply XORing three raw disk images together byte-by-byte is conceptually invalid for RAID 5 reconstruction because parity blocks are distributed and rotate across disks on a per-stripe basis. XORing all disks at every offset would sum data and parity blocks indiscriminately, producing output that is meaningless except by coincidence. Correct reconstruction requires knowing which disk holds the parity block for each stripe, the stripe size, and the parity rotation algorithm (left/right, synchronous/asynchronous), then selectively XORing only the surviving data and parity blocks to rebuild the missing data—not a blind whole-image XOR.
- ✓
Use EnCase to perform a RAID rebuild with known parameters
Why this is correct
EnCase (and similar forensic tools like X-Ways or FTK Imager) can reconstruct a logical RAID 5 volume from disk images by letting you specify the disk order, stripe size, and parity rotation scheme. Once the parameters are set, the tool virtually reassembles the array in memory or as a new image, making the filesystem visible for standard forensic analysis. This is the correct approach when the original RAID metadata is unavailable or partially damaged, as the tool can also parse controller metadata or accept manual input to recover the array.
Quick reference
RAID Level Comparison
| RAID Level | Min Disks | Fault Tolerance | Read | Write | Usable Capacity |
|---|---|---|---|---|---|
| RAID 0 | 2 | None | Excellent | Excellent | 100% |
| RAID 1 | 2 | 1 disk | Good | Moderate | 50% |
| RAID 5 | 3 | 1 disk | Good | Moderate | 67–94% |
| RAID 6 | 4 | 2 disks | Good | Lower | 50–88% |
| RAID 10 | 4 | 1 disk per mirror | Excellent | Good | 50% |
RAID is not a backup strategy — it protects against disk failure but not against accidental deletion, ransomware, or site-level events.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CHFI practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CHFI exam.