Computer Fundamentals (3): Storage Systems - Complete Guide from HDD to SSD
Chen Kai BOSS
  2023-02-14 00:00:00 2023-02-14 00:00      5.1k Words  32 Mins  

Why can an SSD "resurrect" a slow computer? Why does a TLC SSD last 5+ years despite 1000 P/E cycles? Why did your new SSD's speed drop from 500MB/s to 50MB/s? This third part of the Computer Fundamentals Deep Dive Series comprehensively analyzes storage systems: HDD vs SSD working principles, SATA vs NVMe interface speed differences, SLC/MLC/TLC/QLC lifespan calculations, SSD optimization (4K alignment, TRIM, OP), RAID array data protection, and disk troubleshooting and data recovery. Through detailed benchmarks, clear analogies, and rich practical cases, you'll become a storage expert.

Series Navigation

πŸ“š Computer Fundamentals Deep Dive Series (5 Parts): 1. CPU & Computing Core 2. Memory & High-Speed Cache 3. β†’ Storage Systems (HDD vs SSD, interfaces, RAID, recovery) ← You are here 4. Motherboard, Graphics & Expansion 5. Network, Power & Practical Troubleshooting

Part 1: HDD vs SSD - Battle of Generations

HDD (Hard Disk Drive): The Traditional Guardian

Working principle: Magnetic storage on spinning platters

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Inside an HDD:
   β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”
   β”‚ Read/Write β”‚ ← Actuator arm (like record player needle)
   β”‚  Head   β”‚
   β””β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”˜
        ↓
   ╔═══════╗
   β•‘ Platter β•‘ ← Spins at 5400/7200/10000 RPM
   β•šβ•β•β•β•β•β•β•β•
   Data stored on magnetic coating

Analogy: HDD = Vinyl record player

  • Platter = Record (stores data)
  • Head = Needle (reads data)
  • RPM = Rotation speed

Pros:

  • βœ… Large capacity: 2TB-20TB, max 24TB single drive
  • βœ… Cheap: 50/TB)
  • βœ… Long lifespan: 5-10 years normal use
  • βœ… Data recoverable: Possible to recover after failure

Cons:

  • ❌ Slow: Sequential 100-200 MB/s
  • ❌ Shock-sensitive: Movement while running can damage heads
  • ❌ Noisy: Platter spin + head movement audible
  • ❌ High power: 5-10W (SSD only 2-5W)
  • ❌ High latency: Random access 10-15ms

SSD (Solid State Drive): The Speed Revolution

Working principle: NAND flash storage (like USB drives)

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SSD internal structure:
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ Controller IC β”‚ ← Manages data, wear leveling
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ NAND Flash   β”‚ ← Stores data (SLC/MLC/TLC/QLC)
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚ DRAM Cache   β”‚ ← Accelerates R/W (high-end SSDs)
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Pros:

  • βœ… Extremely fast:
    • SATA SSD: 500-550 MB/s
    • NVMe PCIe 3.0: 3500 MB/s
    • NVMe PCIe 4.0: 7000 MB/s
    • PCIe 5.0: 10000+ MB/s
  • βœ… Shock-resistant: No moving parts
  • βœ… Silent: Completely quiet
  • βœ… Low power: 2-5W
  • βœ… Compact: M.2 SSD size of stick of gum
  • βœ… Low random latency: 100ΞΌ s vs HDD's 10ms

Cons:

  • ❌ Expensive: 15/TB)
  • ❌ Limited lifespan: TLC ~1000 P/E cycles
  • ❌ Smaller capacity: Mainstream 512GB-2TB
  • ❌ Hard to recover: Nearly impossible after failure
  • ❌ Data loss risk on power failure: Low probability but exists

Performance Benchmarks

Operation HDD (7200RPM) SATA SSD NVMe 3.0 NVMe 4.0 Speedup
Boot Windows 85s 22s 15s 12s 7.1x
Open Chrome 8.3s 2.1s 1.4s 1.1s 7.5x
Load GTA V 112s 35s 28s 22s 5.1x
Copy 50GB 8min 2.5min 35s 25s 19.2x
4K Random 0.8 MB/s 35 MB/s 50 MB/s 75 MB/s 93.8x

Conclusion: SSD is the most impactful upgrade for user experience!

Part 2: SSD NAND Types - Lifespan Secrets

NAND Flash Classification

Type Bits/Cell States P/E Cycles Speed Price Use Case
SLC 1 bit 2 (0/1) 100,000 β˜…β˜…β˜…β˜…β˜… $

$$$β˜†

β˜†β˜†| Mainstream βœ… | | QLC | 4 bits | 16 (0000-1111) | 500 | β˜…β˜…β˜†β˜†β˜† |$| Warehouse storage |

Lifespan Calculation Example

Scenario: 512GB TLC SSD, daily write 50GB (heavy use)

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Total writes (TBW) = 512GB Γ— 1000 cycles = 512,000GB = 512TB

Theoretical lifespan = 512TB Γ· (50GB/day Γ— 365 days/year) β‰ˆ 28 years

Light use (10GB/day): 

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Lifespan = 512TB Γ· (10GB/day Γ— 365 days/year) β‰ˆ 140 years

Conclusion: TLC SSD lifespan is more than sufficient for typical users!

Part 3: SSD Optimization

4K Alignment

Performance impact:

  • Unaligned: Speed drops 30-50% ❌
  • Aligned: Normal performance βœ…

Check (Windows PowerShell): 

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Get-WmiObject -Class Win32_DiskPartition | Select Name, StartingOffset

# Check if StartingOffset divisible by 4096
# Example: 1048576 Γ· 4096 = 256 (aligned βœ…)

Enable TRIM

Check status (Windows): 

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fsutil behavior query DisableDeleteNotify

Returns:

- 0 β†’ TRIM enabled βœ…
- 1 β†’ TRIM disabled ❌

Enable manually: 

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fsutil behavior set DisableDeleteNotify 0

OP (Over-Provisioning)

Recommendation: Reserve 10-15% space unused

  • 512GB SSD β†’ Partition only 450GB
  • 1TB SSD β†’ Partition only 900GB

Benefits:

  • More stable performance
  • 20-30% longer lifespan

Part 4: RAID Arrays

RAID Level Comparison

RAID Min Disks Capacity Read Write Reliability Use Case
RAID 0 2 100% β˜…β˜…β˜…β˜…β˜… β˜…β˜…β˜…β˜…β˜… β˜…β˜†β˜† Temp data
RAID 1 2 50% β˜…β˜…β˜…β˜…β˜† β˜…β˜…β˜…β˜†β˜† β˜…β˜…β˜…β˜…β˜… Critical data
RAID 5 3 75-90% β˜…β˜…β˜…β˜…β˜† β˜…β˜…β˜…β˜†β˜† β˜…β˜…β˜…β˜…β˜† Enterprise
RAID 10 4 50% β˜…β˜…β˜…β˜…β˜… β˜…β˜…β˜…β˜…β˜† β˜…β˜…β˜…β˜…β˜… Mission-critical

Summary

HDD mechanical slow but large, SSD solid fast but limited lifespan;

SATA entry NVMe flagship, PCIe gen determines bandwidth;

SLC/MLC/TLC/QLC P/E cycles, TLC mainstream thousand enough;

4K align TRIM enable OP reserve, three tricks extend life maintain perf;

RAID 0 fast RAID 1 stable, RAID 5 balanced RAID 10 ultimate!

Next: Motherboard, Graphics & Expansion!

Part 5: RAID Configuration Guide

Software RAID on Windows

Steps (RAID 0 example): 

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1. Prepare two identical-capacity disks (new or backed up)
2. Win+X β†’ Disk Management
3. Right-click disk β†’ Delete Volume (wipe data)
4. Right-click unallocated space β†’ New Striped Volume
5. Select both disks
6. Complete wizard
7. Format as NTFS

Warning: RAID 0 - if any disk fails, all data lost!

Hardware RAID Cards

When needed:

  • Enterprise servers (high data importance)
  • NAS storage (multi-disk management)
  • Performance requirements (software RAID has CPU overhead)

Advantages:

  • βœ… Better performance (dedicated chip)
  • βœ… No CPU resource usage
  • βœ… Hot-swap support (replace failed disk directly)
  • ❌ Expensive (500+)

Part 6: Data Backup Strategy - 3-2-1 Rule

The 3-2-1 Principle

3 copies:

  • 1 original
  • 2 backups

2 media types:

  • Local disk
  • Cloud storage or external drive

1 off-site:

  • Protects against fire, flood, theft

Real Backup Scenarios

Scenario 1: Personal User 

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Important data (photos, documents):

- Primary: Local SSD
- Backup 1: External HDD (weekly backup)
- Backup 2: Cloud (OneDrive/Google Drive, real-time sync)

Scenario 2: Small Studio 

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Project files:

- Primary: Workstation NVMe SSD
- Backup 1: NAS (RAID 1) daily auto-backup
- Backup 2: Cloud storage (off-site disaster recovery)

Scenario 3: Enterprise 

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Database:

- Primary: Server RAID 10 SSD
- Backup 1: Local tape library (daily full)
- Backup 2: Remote datacenter mirror (real-time)

Part 7: Complete PC Building Guide

Tool Checklist

Tool Purpose Necessity
Phillips screwdriver Screws β˜…β˜…β˜…β˜…β˜…
Anti-static wrist strap Prevent ESD damage β˜…β˜…β˜…β˜†
Cable ties Cable management β˜…β˜…β˜…β˜†
Thermal paste CPU cooling β˜…β˜…β˜…β˜…β˜†

Building Steps (Simplified)

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1. Install CPU to motherboard
   ↓
2. Install CPU cooler
   ↓
3. Install RAM (note slot positions)
   ↓
4. Mount motherboard in case
   ↓
5. Install PSU
   ↓
6. Connect motherboard power (24pin + 8pin)
   ↓
7. Install GPU in PCIe slot
   ↓
8. Connect GPU power (6pin/8pin)
   ↓
9. Install SSD/HDD
   ↓
10. Connect all data cables (SATA/front USB etc.)
   ↓
11. Cable management and securing
   ↓
12. Power on test

Part 8: Troubleshooting Case Collection (30+)

Boot Issues (10 cases)

1. No response when pressing power button

  • βœ… Check power cable
  • βœ… Check PSU switch
  • βœ… Check jumper wire (PWR_SW)

2. Fans spin but no display

  • βœ… Reseat RAM (80% success rate)
  • βœ… Check monitor cable
  • βœ… Clear CMOS

3. Automatic restart on boot

  • βœ… Check CPU power (8pin)
  • βœ… Check if RAM seated properly
  • βœ… Test if PSU wattage insufficient

4. Stuck at BIOS screen

  • βœ… Unplug all USB devices
  • βœ… Restore BIOS default settings
  • βœ… Update BIOS

5. Blue screen error codes

  • MEMORY_MANAGEMENT β†’ Memory issue
  • IRQL_NOT_LESS_OR_EQUAL β†’ Driver conflict
  • PAGE_FAULT β†’ Disk bad sector or memory

Performance Issues (10 cases)

6. Computer suddenly slow

  • βœ… Task Manager check resource usage
  • βœ… Check disk health
  • βœ… Clean startup items

7. Low gaming FPS

  • βœ… Is monitor plugged into GPU (not motherboard)?
  • βœ… Is GPU driver latest version?
  • βœ… Power mode set to "High Performance"?

8. SSD speed plummets

  • βœ… Check free space (> 20%)
  • βœ… Confirm 4K alignment
  • βœ… Enable TRIM

9. Frequent program crashes

  • βœ… Check memory usage
  • βœ… Close background programs
  • βœ… Check for overheating

10. Computer overheating

  • βœ… Clean dust from fans and heatsinks
  • βœ… Replace thermal paste (every 2-3 years)
  • βœ… Improve case airflow

Network Issues (10 cases)

11. Network frequently disconnects

  • βœ… Replace ethernet cable
  • βœ… Update NIC driver
  • βœ… Check router settings

12. WiFi signal full but slow

  • βœ… Check frequency band (2.4G vs 5G)
  • βœ… Change WiFi channel
  • βœ… Check for interference devices

13. Cannot connect to internet

  • βœ… Check IP configuration
  • βœ… Reset router
  • βœ… Check DNS settings (try 8.8.8.8)

14. Slow LAN transfer

  • βœ… Check cable category (CAT5e minimum)
  • βœ… Check NIC negotiation speed
  • βœ… Check switch performance

15. VPN won't connect

  • βœ… Check firewall settings
  • βœ… Check router port forwarding
  • βœ… Try different VPN protocol

❓ Q&A: Storage Systems Common Questions

SSD vs HDD - When to Use Each?

Quick Decision Matrix:

Scenario Recommended Drive Reason
OS/Boot drive SSD (SATA or NVMe) 5-7x faster boot, instant app launches
Gaming NVMe SSD Fast level loading, texture streaming
Video editing NVMe SSD + HDD SSD for active projects, HDD for archive
Photo storage HDD Large capacity, cost-effective ($15/TB)
NAS/Server HDD (RAID) 8-20TB capacity, 24/7 reliability
Laptop SSD only Power efficiency, shock resistance
Budget build Small SSD + Large HDD 256GB SSD boot + 2TB HDD storage

Real-World Example: 

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Budget Gaming PC ($800):

- 500GB NVMe SSD ($50) β†’ Windows + 3-4 games
- 2TB HDD ($30) β†’ Game library, media files
Total:$80 for 2.5TB hybrid solution

vs. All-SSD ($200 for 2.5TB) β†’ Save$120!

When HDD Still Wins:

  • βœ… Cold storage: Photos, videos, documents you rarely access
  • βœ… Backup drives: External HDDs for 3-2-1 backup strategy
  • βœ… NAS systems: 4-8 bay NAS with RAID for home media server
  • βœ… Budget constraints: 50-100/TB for SSD

NVMe vs SATA SSD - Performance Differences

Interface Comparison:

Feature SATA SSD NVMe PCIe 3.0 NVMe PCIe 4.0 NVMe PCIe 5.0
Max Sequential Read 550 MB/s 3,500 MB/s 7,000 MB/s 12,000+ MB/s
Max Sequential Write 520 MB/s 3,200 MB/s 6,000 MB/s 10,000+ MB/s
4K Random Read (IOPS) 90,000 600,000 1,000,000 1,500,000+
Latency 100 ΞΌ s 50 ΞΌ s 30 ΞΌ s 20 ΞΌ s
Interface SATA 3.0 (6 Gbps) PCIe 3.0 x4 (32 Gbps) PCIe 4.0 x4 (64 Gbps) PCIe 5.0 x4 (128 Gbps)
Form Factor 2.5" or M.2 M.2 (most common) M.2 M.2
Price (1TB) $60-80 $80-120 $120-180 $200+

When You'll Notice the Difference:

SATA SSD is sufficient for:

  • βœ… General office work, web browsing
  • βœ… Light gaming (indie games, older titles)
  • βœ… Boot drive for budget builds
  • βœ… Laptops with only SATA M.2 slot

NVMe PCIe 3.0 makes sense for:

  • βœ… Gaming (AAA titles with large textures)
  • βœ… Content creation (video editing, 3D rendering)
  • βœ… Database workloads
  • βœ… Virtual machines

NVMe PCIe 4.0/5.0 for:

  • βœ… Professional video editing (8K RAW footage)
  • βœ… High-frequency trading systems
  • βœ… Scientific computing (large dataset processing)
  • βœ… Future-proofing (next-gen games)

Practical Test Results: 

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Task: Copy 100GB game folder

- SATA SSD: 3 min 20 sec
- NVMe 3.0: 28 sec (7x faster)
- NVMe 4.0: 18 sec (11x faster)

Task: Boot Windows 11

- SATA SSD: 22 sec
- NVMe 3.0: 15 sec (noticeable but not dramatic)
- NVMe 4.0: 12 sec (marginal improvement)

Bottom Line: For most users, SATA SSD is 80% of NVMe performance at 60% of the cost. NVMe shines in professional workloads and heavy multitasking.

TLC vs QLC NAND - Durability Trade-offs

NAND Type Comparison:

Metric TLC (3-bit) QLC (4-bit)
P/E Cycles 1,000-3,000 500-1,000
Sequential Write 500-550 MB/s 400-500 MB/s
Random Write 80,000 IOPS 40,000 IOPS
Price (1TB) $80-120 $60-90
Use Case Mainstream, gaming Budget, storage
Lifespan (50GB/day) 28+ years 14+ years

Durability Calculation:

TLC Example (1TB TLC SSD, 1000 P/E cycles): 

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Total Writes = 1TB Γ— 1000 = 1,000TB (1PB)

Daily Write: 50GB (heavy user)
Lifespan = 1,000TB Γ· (50GB/day Γ— 365 days/year) = 54.8 years

Daily Write: 20GB (moderate user)
Lifespan = 1,000TB Γ· (20GB/day Γ— 365 days/year) = 137 years

QLC Example (1TB QLC SSD, 500 P/E cycles): 

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Total Writes = 1TB Γ— 500 = 500TB

Daily Write: 50GB
Lifespan = 500TB Γ· (50GB/day Γ— 365 days/year) = 27.4 years

Daily Write: 20GB
Lifespan = 500TB Γ· (20GB/day Γ— 365 days/year) = 68.5 years

Real-World Considerations:

Choose TLC if:

  • βœ… You write large files frequently (video editing, game recording)
  • βœ… You want maximum performance consistency
  • βœ… You use the drive as OS/boot drive
  • βœ… Price difference is acceptable ($20-30 more)

QLC is fine if:

  • βœ… You're on a tight budget
  • βœ… Drive is mostly read-only (game library, media storage)
  • βœ… You have good backup habits (3-2-1 rule)
  • βœ… You upgrade hardware every 3-5 years anyway

Performance Degradation: 

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QLC drives slow down significantly when:

- Free space < 20% (SLC cache exhausted)
- Sustained writes > 100GB (cache fills up)
- Drive is 70%+ full

TLC maintains better performance under these conditions.

Recommendation: For boot drives and primary storage, choose TLC. For secondary storage and game libraries, QLC is acceptable if budget-constrained.

RAID Levels Explained - Which for Home/Work?

RAID Level Decision Guide:

RAID Level Disks Needed Usable Capacity Read Speed Write Speed Fault Tolerance Best For
RAID 0 2+ 100% β˜…β˜…β˜…β˜…β˜… β˜…β˜…β˜…β˜…β˜… None (1 disk = total loss) Temp files, scratch disk
RAID 1 2 50% β˜…β˜…β˜…β˜…β˜† β˜…β˜…β˜…β˜†β˜† 1 disk failure Home NAS, critical data
RAID 5 3+ (n-1)/n β˜…β˜…β˜…β˜…β˜† β˜…β˜…β˜…β˜†β˜† 1 disk failure Small business server
RAID 10 4+ (even) 50% β˜…β˜…β˜…β˜…β˜… β˜…β˜…β˜…β˜…β˜† Multiple disk failures Enterprise, mission-critical

Home Use Scenarios:

Scenario 1: Home Media Server (4-bay NAS) 

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Setup: 4Γ— 4TB HDDs in RAID 5
Result: 12TB usable, 1 disk failure protection
Cost: ~$400 for drives
Use: Store movies, photos, backups
Alternative: RAID 1 (2Γ— 8TB = 8TB usable, simpler)

Scenario 2: Gaming PC with Multiple SSDs 

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Setup: 2Γ— 1TB NVMe SSDs in RAID 0
Result: 2TB, 2x read/write speed
Risk: If one fails, all data lost
Better: Use separately (OS on one, games on other)

Scenario 3: Workstation for Video Editing 

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Setup: 4Γ— 2TB SSDs in RAID 10
Result: 4TB usable, fast + redundant
Cost: High ($800+)
Alternative: 2Γ— 4TB SSDs in RAID 1 (simpler, cheaper)

Work/Business Scenarios:

Small Business Server:

  • RAID 5 (3-5 disks): Good balance of capacity and protection
  • RAID 10 (4+ disks): Maximum performance + redundancy

Database Server:

  • RAID 10: Best random I/O performance
  • RAID 5: Acceptable for read-heavy workloads

Backup Server:

  • RAID 1 or RAID 6: Prioritize data protection over speed

RAID Calculator Example: 

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RAID 5 with 4Γ— 4TB drives:

- Total: 16TB raw
- Usable: 12TB (one disk for parity)
- Protection: Can lose 1 disk
- Rebuild time: 8-12 hours (depends on disk speed)

RAID 10 with 4Γ— 4TB drives:

- Total: 16TB raw
- Usable: 8TB (50% overhead)
- Protection: Can lose 1 disk per mirror pair (up to 2 if different pairs)
- Rebuild time: 2-4 hours (faster, mirrors smaller)

Recommendation:

  • Home: RAID 1 (simple, safe) or RAID 5 (more capacity)
  • Work: RAID 10 (performance-critical) or RAID 6 (large arrays, 2-disk protection)

4K Alignment - Why It Matters

What is 4K Alignment?

Modern SSDs read/write data in 4KB blocks (4096 bytes). If your partition doesn't start at a 4KB boundary, a single write operation might span two physical blocks, requiring two I/O operations instead of one.

Performance Impact:

Alignment Status Sequential Read Sequential Write Random Read Random Write
Aligned 550 MB/s 520 MB/s 90,000 IOPS 85,000 IOPS
Unaligned 380 MB/s (-31%) 340 MB/s (-35%) 60,000 IOPS (-33%) 55,000 IOPS (-35%)

Why This Happens:

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Unaligned partition (starts at byte 512):
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ Sector 0 (512B) β”‚ Sector 1 (512B) β”‚ ... β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
         ↑
    Partition starts here

SSD physical block (4KB = 8 sectors):
β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ Block 0 (4KB) β”‚ Block 1 (4KB) β”‚ ... β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Writing 4KB data requires:

- Read Block 0 (modify first part)
- Read Block 1 (modify second part)
- Write Block 0
- Write Block 1
= 4 operations instead of 1!

How to Check Alignment:

Windows (PowerShell): 

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Get-WmiObject -Class Win32_DiskPartition | 
  Select Name, StartingOffset | 
  Format-Table -AutoSize

# Check: StartingOffset Γ· 4096 = whole number?
# Example: 1048576 Γ· 4096 = 256 βœ… (aligned)
# Example: 512 ÷ 4096 = 0.125 ❌ (unaligned)

Windows (Command Prompt): 

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wmic partition get Name, StartingOffset

# Divide StartingOffset by 4096
# If result is whole number β†’ aligned βœ…

Linux: 

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sudo fdisk -l /dev/sda
# Check "Start" column, divide by 8 (sectors)
# If divisible by 8 β†’ aligned βœ…

How to Fix (if unaligned):

Windows: 1. Backup all data 2. Delete partition 3. Create new partition (Windows 7+ auto-aligns) 4. Or use: diskpart β†’ create partition primary align=4096

Linux: 

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# Use fdisk/gdisk with proper alignment
# Start partition at sector 2048 (1MB offset, always aligned)

Modern OS Note: Windows 7+ and modern Linux distributions automatically align partitions during installation. You only need to check if:

  • Drive was partitioned on older OS (Windows XP, Vista)
  • You manually created partitions with old tools
  • You cloned a drive from an older system

Bottom Line: Misalignment can cost you 30-35% performance. Always verify alignment, especially when migrating from old systems.

SSD TRIM and Garbage Collection

What is TRIM?

TRIM is a command that tells the SSD which data blocks are no longer in use (deleted files). This allows the SSD to proactively erase these blocks during idle time, keeping write performance consistent.

Without TRIM: 

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Day 1: Write 100GB of data
Day 30: Delete 50GB
Day 60: Write 50GB new data

Without TRIM:

- SSD doesn't know blocks are free
- Must erase blocks during write (slow!)
- Write speed: 500 MB/s β†’ 150 MB/s ❌

With TRIM:

- SSD knows blocks are free immediately
- Erases blocks during idle time
- Write speed: 500 MB/s β†’ 480 MB/s βœ…

How TRIM Works:

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1. OS deletes file
   ↓
2. OS sends TRIM command to SSD
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3. SSD marks blocks as "invalid"
   ↓
4. SSD erases blocks during idle time (garbage collection)
   ↓
5. Blocks ready for fast writes

Enable TRIM:

Windows (usually enabled by default): 

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# Check status
fsutil behavior query DisableDeleteNotify
# Returns: 0 = enabled βœ…, 1 = disabled ❌

# Enable manually
fsutil behavior set DisableDeleteNotify 0

# Run TRIM manually (Windows 8+)
Optimize-Volume -DriveLetter C -ReTrim -Verbose

Linux: 

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# Check if TRIM supported
lsblk -o NAME,DISC-MAX
# DISC-MAX > 0 = TRIM supported

# Enable TRIM in /etc/fstab
UUID=xxx / ext4 defaults,noatime,discard 0 1

# Or run TRIM manually (weekly cron job)
sudo fstrim -v /

macOS: TRIM enabled automatically for Apple SSDs. For third-party SSDs: 

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sudo trimforce enable

Garbage Collection (GC):

Garbage collection is the SSD controller's process of erasing invalid blocks and consolidating valid data. It happens in two modes:

Idle GC (background, when drive is idle):

  • βœ… Doesn't impact performance
  • βœ… Maintains consistent speeds
  • Requires TRIM to know which blocks are invalid

Active GC (during writes, if drive is full):

  • ⚠️ Can slow down writes
  • ⚠️ Happens when free space < 20%
  • ⚠️ More common on QLC drives

Performance Impact:

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SSD with TRIM enabled:

- Fresh drive: 550 MB/s write
- After 1 year: 540 MB/s write (2% degradation) βœ…

SSD without TRIM:

- Fresh drive: 550 MB/s write
- After 1 year: 200 MB/s write (64% degradation) ❌

Best Practices: 1. βœ… Always enable TRIM (modern OS do this automatically) 2. βœ… Keep 15-20% free space (gives GC room to work) 3. βœ… Don't defragment SSDs (wastes write cycles, TRIM handles it) 4. βœ… Use native TRIM (not third-party "SSD optimizers")

Storage Health Monitoring - SMART Attributes

What is SMART?

SMART (Self-Monitoring, Analysis, and Reporting Technology) is a monitoring system built into storage drives. It tracks various attributes that indicate drive health and predict failures.

Critical SMART Attributes:

Attribute Meaning Warning Threshold Critical
Reallocated Sectors Bad sectors replaced with spares > 10 > 100
Power-On Hours Total hours drive has been on > 20,000 > 50,000
Power Cycle Count Number of on/off cycles > 10,000 > 20,000
Wear Leveling Count SSD: Remaining P/E cycles < 20% < 10%
Temperature Current drive temperature > 60Β° C > 70Β° C
Uncorrectable Errors Data errors that couldn't be fixed > 0 > 10
CRC Errors Interface communication errors > 10 > 100

How to Check SMART Data:

Windows (free tools):

  • CrystalDiskInfo: Visual interface, color-coded health status
  • HD Tune: Detailed SMART table + benchmark
  • PowerShell: Get-PhysicalDisk | Get-StorageReliabilityCounter

Linux: 

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# Install smartmontools
sudo apt install smartmontools

# Check SMART status
sudo smartctl -a /dev/sda

# Quick health check
sudo smartctl -H /dev/sda
# Returns: PASSED or FAILED

macOS: 

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# Check SMART status
diskutil info disk0 | grep "SMART Status"
# Or use: smartctl (install via Homebrew)

Interpreting Results:

Healthy Drive: 

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Reallocated Sectors: 0
Power-On Hours: 5,234
Temperature: 35Β° C
Wear Leveling: 95% remaining
Status: PASSED βœ…

Warning Signs: 

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Reallocated Sectors: 45 (increasing)
Uncorrectable Errors: 3
Status: CAUTION ⚠️
Action: Backup immediately, replace soon

Critical/Failing: 

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Reallocated Sectors: 250 (spare pool exhausted)
Uncorrectable Errors: 15
Status: FAILED ❌
Action: Replace immediately, data at risk

Real-World Monitoring Strategy:

Home Users:

  • Check SMART monthly (set calendar reminder)
  • Use CrystalDiskInfo (Windows) or smartctl (Linux)
  • Backup when any attribute shows warning

Business/Server:

  • Automated monitoring (Nagios, Zabbix)
  • Email alerts on threshold breaches
  • Proactive replacement before failure

Example Alert Setup (Linux cron): 

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# Weekly SMART check script
#!/bin/bash
SMART_STATUS=$(smartctl -H /dev/sda | grep "PASSED")
if [ -z "$SMART_STATUS" ]; then
    echo "WARNING: Drive /dev/sda may be failing!" | mail -s "SMART Alert" admin@example.com
fi

Temperature Monitoring:

Optimal Temperatures:

  • HDD: 30-40Β° C (idle), 40-50Β° C (active)
  • SSD: 30-50Β° C (idle), 50-70Β° C (active, acceptable)

High Temperature Impact:

  • HDD: > 60Β° C β†’ Increased failure rate
  • SSD: > 70Β° C β†’ Throttling, reduced lifespan

Cooling Tips:

  • Ensure case airflow (front intake, rear exhaust)
  • Add drive bay fans if needed
  • Avoid stacking drives without spacing
  • Monitor with SMART temperature attribute

Data Backup Strategies - 3-2-1 Rule

The 3-2-1 Backup Rule:

3 Copies: Original + 2 backups 2 Media Types: Different storage technologies 1 Off-Site: Geographic separation

Why This Matters:

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Disaster Scenarios:

- Fire/flood: Destroys all local copies β†’ Need off-site backup βœ…
- Ransomware: Encrypts all connected drives β†’ Need air-gapped backup βœ…
- Drive failure: One backup fails β†’ Second backup saves you βœ…
- Theft: Laptop + external drive stolen β†’ Cloud backup saves you βœ…

Implementation Examples:

Personal User (Budget:$100/year): 

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Primary: Laptop SSD (500GB)
β”œβ”€ Backup 1: External HDD (1TB, $50, weekly manual backup)
└─ Backup 2: Cloud storage (Google Drive/OneDrive,$60/year, auto-sync)

Media Types: SSD + HDD + Cloud βœ…
Off-Site: Cloud backup βœ…
Cost: ~$110 one-time +$60/year

Photographer (Budget: $300/year): 

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Primary: Workstation NVMe SSD (2TB)
β”œβ”€ Backup 1: NAS RAID 1 (2Γ— 4TB HDD,$200, hourly auto-backup)
└─ Backup 2: Cloud storage (Backblaze B2, $5/TB/month =$120/year)

Media Types: SSD + HDD + Cloud βœ…
Off-Site: Cloud backup βœ…
Cost: ~$320 one-time +$120/year

Small Business (Budget: $2000/year): 

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Primary: Server RAID 10 (8Γ— 2TB SSD)
β”œβ”€ Backup 1: Local tape library (daily full backup,$500)
└─ Backup 2: Remote datacenter mirror (real-time sync, $1500/year)

Media Types: SSD + Tape + Cloud βœ…
Off-Site: Remote datacenter βœ…
Cost: ~$500 one-time +$1500/year

Backup Frequency Guide:

Data Type Backup Frequency Retention Storage Location
OS/Programs Monthly (image backup) 3 months External HDD
Documents Daily (auto-sync) 1 year Cloud + External HDD
Photos/Videos Weekly (incremental) Forever Cloud + NAS
Code/Projects Real-time (Git) Forever GitHub + Local clone
Database Hourly (transaction log) 30 days Remote server

Backup Tools:

Windows:

  • File History: Built-in, simple file backup
  • Windows Backup: Full system image
  • Veeam Agent: Free, enterprise-grade
  • Macrium Reflect: Paid, excellent imaging

Linux:

  • rsync: Command-line, flexible
  • Timeshift: System snapshot (like macOS Time Machine)
  • BorgBackup: Deduplication, encryption
  • Rclone: Cloud sync tool

macOS:

  • Time Machine: Built-in, automatic
  • Carbon Copy Cloner: Advanced cloning
  • SuperDuper!: Disk cloning

Cloud Backup Services:

Service Price (1TB) Pros Cons
Backblaze B2 $5/month Cheap, fast Pay per GB downloaded
AWS S3 $23/month Reliable, scalable Complex pricing
Google Drive $10/month Integrated with Gmail Privacy concerns
OneDrive $7/month Integrated with Office Microsoft ecosystem
iCloud $10/month Seamless on Apple devices Expensive for large storage

Testing Your Backups:

Quarterly Backup Test: 1. βœ… Verify backup files are accessible 2. βœ… Test restore one file (document, photo) 3. βœ… Test restore full folder 4. βœ… Check backup logs for errors 5. βœ… Verify off-site backup is current

Disaster Recovery Drill (annual): 1. Simulate drive failure 2. Restore from backup 3. Measure recovery time 4. Document process 5. Update backup strategy if needed

Common Backup Mistakes:

❌ Only one backup (single point of failure) ❌ All backups on same drive (defeats purpose) ❌ Never testing backups (backup might be corrupted) ❌ No off-site backup (fire/flood destroys everything) ❌ Infrequent backups (lose weeks of work) ❌ No versioning (can't recover older versions)

Bottom Line: The 3-2-1 rule is the minimum for important data. For critical business data, consider 3-2-1-1-0 (add air-gapped and immutable backups).

Summary & Complete Cheat Sheet

HDD mechanical slow but large, SSD solid fast but limited life;

SATA entry NVMe flagship, PCIe gen determines bandwidth;

SLC/MLC/TLC/QLC P/E cycles, TLC mainstream thousand sufficient;

4K align TRIM enable OP reserve, three tricks extend life maintain perf;

RAID 0 fast RAID 1 stable, RAID 5 balanced RAID 10 ultimate;

Bad sector check chkdsk, critical data backup immediately;

3-2-1 backup rule remember, dual media one off-site;

Build PC tools ready, troubleshoot methodically case by case!

🎊 Computer Fundamentals Series Complete!

Through these 5 articles, you've mastered:

  • βœ… Hardware purchasing without getting scammed
  • βœ… Clear performance optimization strategies
  • βœ… Systematic troubleshooting approaches
  • βœ… Confident PC building and maintenance

Next steps: 1. Build a PC hands-on (best learning method) 2. Help friends troubleshoot (consolidate knowledge) 3. Follow new tech (DDR5, PCIe 5.0, WiFi 7)

Thank you for reading! Congratulations on becoming a hardware expert! πŸŽ“

πŸŽ“ Summary: Storage Systems Cheat Sheet

Quick Reference Tables

Drive Type Selection:

Use Case Recommended Capacity Budget
OS Boot NVMe PCIe 3.0 SSD 500GB-1TB $80-120
Gaming NVMe PCIe 3.0/4.0 SSD 1-2TB $100-200
Video Editing NVMe PCIe 4.0 SSD 2-4TB $200-400
Photo Archive HDD (7200 RPM) 4-8TB $60-120
NAS Storage HDD (RAID) 8-20TB $200-500
Budget Build SATA SSD + HDD 256GB + 2TB $80

Interface Speed Comparison:

Interface Max Speed Real-World Use Case
SATA 3.0 6 Gbps (600 MB/s) 550 MB/s Entry-level SSD
PCIe 3.0 x4 32 Gbps (4 GB/s) 3,500 MB/s Mainstream NVMe
PCIe 4.0 x4 64 Gbps (8 GB/s) 7,000 MB/s High-end NVMe
PCIe 5.0 x4 128 Gbps (16 GB/s) 12,000+ MB/s Flagship NVMe

NAND Flash Types:

Type P/E Cycles Speed Price Best For
SLC 100,000 β˜…β˜…β˜…β˜…β˜… $

$$$β˜†

β˜†β˜†| Mainstream βœ… | | QLC | 500-1,000 | β˜…β˜…β˜†β˜†β˜† |$| Budget storage |

RAID Level Quick Guide:

RAID Disks Capacity Speed Protection Use
0 2+ 100% Fastest None Temp files
1 2 50% Fast 1 disk Home NAS
5 3+ (n-1)/n Fast 1 disk Small business
10 4+ 50% Fastest Multiple Enterprise

Performance Benchmarks Summary

Boot Time Comparison:

  • HDD (7200 RPM): 85 seconds
  • SATA SSD: 22 seconds (3.9x faster)
  • NVMe PCIe 3.0: 15 seconds (5.7x faster)
  • NVMe PCIe 4.0: 12 seconds (7.1x faster)

Game Loading (50GB game):

  • HDD: 112 seconds
  • SATA SSD: 35 seconds (3.2x faster)
  • NVMe PCIe 3.0: 28 seconds (4x faster)
  • NVMe PCIe 4.0: 22 seconds (5.1x faster)

4K Random Read (IOPS):

  • HDD: 100 IOPS (0.8 MB/s)
  • SATA SSD: 90,000 IOPS (35 MB/s)
  • NVMe PCIe 3.0: 600,000 IOPS (50 MB/s)
  • NVMe PCIe 4.0: 1,000,000 IOPS (75 MB/s)

SSD Optimization Checklist

Before First Use:

  • βœ… Check 4K alignment (Windows 7+ auto-aligns)
  • βœ… Enable TRIM (usually automatic)
  • βœ… Reserve 15-20% free space (OP - Over-Provisioning)
  • βœ… Update SSD firmware (manufacturer website)

Ongoing Maintenance:

  • βœ… Keep > 20% free space
  • βœ… Don't defragment SSDs
  • βœ… Monitor SMART attributes monthly
  • βœ… Check temperature (< 70Β° C under load)

Performance Troubleshooting:

  • Slow writes β†’ Check free space, enable TRIM
  • Slow boot β†’ Check 4K alignment, update drivers
  • High temperature β†’ Improve case airflow
  • Errors β†’ Check SMART, backup immediately

Lifespan Calculation Formula

SSD Lifespan (Years): 

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Lifespan = (Capacity Γ— P/E Cycles) Γ· (Daily Writes Γ— 365)

Example: 1TB TLC SSD (1000 P/E cycles), 50GB/day writes
Lifespan = (1000GB Γ— 1000) Γ· (50GB Γ— 365) = 54.8 years

Typical Daily Writes:

  • Light user: 10-20 GB/day
  • Moderate user: 20-50 GB/day
  • Heavy user: 50-100 GB/day
  • Professional: 100-500 GB/day

SMART Attributes Quick Reference

Critical Attributes to Monitor:

  • Reallocated Sectors: > 10 = warning, > 100 = critical
  • Wear Leveling Count (SSD): < 20% = warning, < 10% = critical
  • Temperature: > 60Β° C = warning, > 70Β° C = critical
  • Uncorrectable Errors: > 0 = warning, > 10 = critical

Check Commands:

  • Windows: Get-PhysicalDisk | Get-StorageReliabilityCounter
  • Linux: smartctl -a /dev/sda
  • macOS: diskutil info disk0 | grep "SMART Status"

Backup Strategy Templates

Personal User (3-2-1): 

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Primary: Laptop SSD
β”œβ”€ Backup 1: External HDD (weekly)
└─ Backup 2: Cloud storage (auto-sync)
Cost: ~$110 one-time +$60/year

Professional User (3-2-1): 

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Primary: Workstation NVMe SSD
β”œβ”€ Backup 1: NAS RAID 1 (hourly)
└─ Backup 2: Cloud storage (daily)
Cost: ~$500 one-time +$200/year

Enterprise (3-2-1-1-0): 

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Primary: Server RAID 10
β”œβ”€ Backup 1: Local tape (daily)
β”œβ”€ Backup 2: Remote datacenter (real-time)
β”œβ”€ Backup 3: Air-gapped (weekly)
└─ Immutable: Cloud with versioning
Cost: $5000+ one-time +$3000/year

Common Issues & Solutions

Problem Symptom Solution
Slow SSD Write speed drops 50%+ Check free space, enable TRIM, verify 4K alignment
High temperature > 70Β° C under load Improve airflow, check case fans, add drive bay fan
SMART warning Reallocated sectors increasing Backup immediately, replace drive soon
RAID rebuild fails Second disk fails during rebuild Use RAID 6 (2-disk protection) or RAID 10
Backup corruption Can't restore files Test backups quarterly, use multiple backup tools
4K misalignment 30% slower than expected Re-partition with proper alignment (sector 2048)

Cost-Performance Sweet Spots

Best Value Picks (2024):

  • Boot Drive: 500GB NVMe PCIe 3.0 TLC ($60-80)
  • Gaming: 1TB NVMe PCIe 3.0 TLC ($80-100)
  • Storage: 4TB HDD 7200 RPM ($60-80)
  • NAS: 8TB HDD 7200 RPM ($120-150)

When to Splurge:

  • PCIe 4.0: Professional video editing, 8K workflows
  • PCIe 5.0: Future-proofing, extreme workloads
  • RAID 10: Mission-critical databases, high I/O servers
  • Enterprise SSD: 24/7 server workloads, high write volumes

Quick Decision Trees

Choosing Storage Type: 

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Need > 4TB capacity?
β”œβ”€ Yes β†’ HDD (cost-effective)
└─ No β†’ SSD
    β”‚
    Need < 1TB?
    β”œβ”€ Yes β†’ SATA SSD (budget)
    └─ No β†’ NVMe SSD
        β”‚
        Budget <$100?
        β”œβ”€ Yes β†’ PCIe 3.0
        └─ No β†’ PCIe 4.0 (future-proof)

Choosing RAID Level: 

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Need redundancy?
β”œβ”€ No β†’ RAID 0 (fastest, no protection)
└─ Yes β†’ How many disks?
    β”œβ”€ 2 disks β†’ RAID 1 (mirror)
    β”œβ”€ 3-5 disks β†’ RAID 5 (balanced)
    └─ 4+ disks β†’ RAID 10 (best performance + protection)

Backup Strategy: 

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Data importance?
β”œβ”€ Low β†’ Single external drive (monthly)
β”œβ”€ Medium β†’ 3-2-1 rule (external + cloud)
└─ High β†’ 3-2-1-1-0 (add air-gapped + immutable)

Key Takeaways

  1. SSD vs HDD: SSD for speed (OS, apps, games), HDD for capacity (storage, archive)
  2. NVMe vs SATA: NVMe 6-7x faster, but SATA sufficient for most users
  3. TLC vs QLC: TLC for boot drives, QLC acceptable for storage if budget-constrained
  4. RAID: RAID 1 for home, RAID 10 for enterprise, RAID 0 only for temp data
  5. 4K Alignment: Critical for performance, modern OS handle automatically
  6. TRIM: Always enable, maintains consistent SSD performance
  7. SMART Monitoring: Check monthly, backup on any warning
  8. 3-2-1 Backup: Minimum for important data, test quarterly

Further Reading

  • SSD Optimization: Enable TRIM, maintain free space, monitor SMART
  • RAID Configuration: Start with RAID 1, upgrade to RAID 10 if needed
  • Backup Tools: Use native OS tools + cloud sync for best coverage
  • Troubleshooting: Check alignment, temperature, SMART before replacing drive

Remember: Storage is the foundation of your data. Invest wisely, monitor regularly, and backup religiously!

  • Post title：Computer Fundamentals (3): Storage Systems - Complete Guide from HDD to SSD
  • Post author：Chen Kai
  • Create time：2023-02-14 00:00:00
  • Post link：https://www.chenk.top/en/computer-fundamentals-3-storage/
  • Copyright Notice：All articles in this blog are licensed under BY-NC-SA unless stating additionally.
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