Advanced Guide to Network Attached Storage (NAS): RAID and Permission Management

Bought a NAS but only using it like a regular external hard drive? This guide will help you deeply understand RAID configuration principles, user permission management, and how to scientifically plan your NAS usage strategy.

1. In-Depth RAID Principle Analysis

RAID is Not a Backup

This is the most common misconception! The essence of RAID is redundancy, which improves availability, not backup:

RAID protects against hardware failure of hard drives
RAID cannot protect against accidental deletion, ransomware, fire, or theft
True backup requires following the 3-2-1 rule (3 copies of data, 2 different media types, 1 copy offsite)

Detailed Breakdown of Major RAID Types

RAID 0 (Striping)

Principle: Data is written across multiple hard drives, doubling read/write speeds
Capacity Utilization: 100% (uses all N drives)
Safety: If any single drive fails, all data is completely lost
Use Case: Temporary storage for video editing, prioritizing speed without concern for data risk

RAID 1 (Mirroring)

Principle: Two drives store identical data as mirrors of each other
Capacity Utilization: 50% (2 drives provide the capacity of only 1)
Safety: If one drive fails, the other remains intact
Use Case: Small home setups where data safety is the priority and capacity is not the main concern

RAID 5 (Distributed Parity)

Principle: Data and parity blocks are distributed across all drives; data can be recovered if any single drive fails
Minimum Drives: 3
Capacity Utilization: (N-1)/N (3 drives provide usable capacity of 2)
Safety: Allows for 1 drive failure
Risk: Long rebuild time; if another drive fails during rebuild, data is lost (rebuild risk)

RAID 6 (Dual Parity)

Principle: Dual parity allows for 2 drives to fail simultaneously
Minimum Drives: 4
Capacity Utilization: (N-2)/N
Use Case: Very important data with a larger number of drives (4+ bay)

SHR (Synology Hybrid RAID) / JBOD

SHR is a proprietary format from certain brands, supporting mixed use of different capacity hard drives
Suitable for users who plan to expand capacity gradually
Be aware of format compatibility issues when migrating to other devices

Selection Recommendations

Number of Bays	Recommended Configuration	Notes
2-bay	RAID 1	Mirroring protection, simple and reliable
4-bay	RAID 5 or RAID 6	RAID 6 is safer
5-bay+	RAID 6	Large capacity + dual-drive fault tolerance

2. Hard Drive Selection and Health Monitoring

NAS-Specific Drives vs. Regular Desktop Drives

Comparison Item	NAS-Specific Drive	Regular Desktop Drive
7×24 Operation Design	✅ Yes	❌ No
Vibration Compensation	✅ Yes	❌ No
Data Integrity Verification	✅ Supported	Partially Supported
Price	15-30% More Expensive	Cheaper
Lifespan (Continuous Operation)	5+ Years	2-3 Years, Potential Issues

Conclusion: For a NAS running continuously, NAS-specific drives are strongly recommended. It's not worth skimping on hard drives.

SMART Health Monitoring

SMART (Self-Monitoring, Analysis and Reporting Technology) is a hard drive self-monitoring mechanism:

Key Indicators:

Reallocated Sector Count: A value > 0 requires attention; continuous growth means you should back up and replace the drive
Current Pending Sector Count: Sectors pending reallocation; any non-zero value requires attention
Uncorrectable Sector Count: Uncorrectable sectors; a non-zero value is very dangerous
Power On Hours: Total powered-on time; can be used to estimate the drive's "age"

Recommendation: Check SMART data once a month. If any anomalies appear, initiate a data backup plan.

3. User Permissions and Directory Management

Permission Design Principles

Even a home NAS is worth designing permissions carefully to avoid accidental operations or unauthorized access to sensitive data:

User Group Recommendations:

Administrator Account: Not used daily; only logged in for maintenance
Personal Accounts: Each family member has their own account, with access only to their own directory
Family Shared Group: Can access shared media libraries and photo libraries

Directory Structure Recommendations:

/media          → Movies, music (shared, read-only)
/photo-family   → Family photos (shared, writable)
/backup-[name]  → Individual backup directories (accessible only by the person)
/documents      → Important documents (backup priority)

External Access Security

Opening a NAS to external access carries security risks. Here are safety recommendations:

Strong Password + Two-Factor Authentication: NAS accounts must use complex passwords
Change Default Ports: Change default management ports (e.g., 5000, 5001) to non-standard ports
Disable the admin Account: Create a new administrator account and disable the default admin
VPN Access: The safest way to access your NAS externally is via a VPN back to your home network
Regularly Check Login Logs: If you find logins from unusual IP addresses, change your password immediately
Disable Unnecessary Services: Keep non-essential services like SSH and Telnet disabled by default

4. Configuring Practical NAS Features

Photo Backup

Automatically upload phone photos to the NAS for local/cloud dual backup
You can set up a private cloud photo album with facial recognition and map browsing
It is recommended to also keep a cloud backup as an offsite copy

Time Machine Backup

Mac users can configure their NAS as a Time Machine destination:

Set up a dedicated user and shared folder
Limit the maximum space used by Time Machine
Wired network backups are significantly faster than WiFi

Media Server

Supports DLNA streaming to smart TVs
You can set up a private video library for smooth playback on your local network
Pay attention to video format compatibility; h.265/4K requires sufficient decoding power from the NAS

Download Station

Supports BT and magnet link downloads (be aware of copyright laws)
Offline downloading doesn't consume your computer's resources
Use scheduled power on/off to reduce electricity costs and noise

5. Maintenance and Troubleshooting

Regular Maintenance Checklist

Monthly: Check SMART status, review system logs
Quarterly: Check RAID health status, test data integrity
Semi-Annually: Check fan operation, clean dust
Annually: Update system firmware, assess hard drive health

Hard Drive Failure Procedure

Receive a hard drive error alert
Immediately back up critical data to another storage medium
Confirm the RAID status (degraded mode is still usable but has no redundancy)
Purchase a replacement drive of the same capacity or larger
Hot-swap the drive (on supported models) and wait for the rebuild to complete
Do not shut down or replace another drive until the rebuild is finished

📌 Core Advice: RAID provides protection against hard drive failure, but true data security requires following the 3-2-1 backup principle. A NAS is just one part of a comprehensive data security system.