Quick answers
The write speed of an external hard drive depends on several factors like the interface type, drive cache, and disk rotation speed. For most users, an external HDD with a USB 3.0 interface and 5400 RPM spin speed offers decent write speeds around 100-130 MB/s. For faster performance, a 7200 RPM external HDD with USB 3.0 can provide write speeds up to 180 MB/s. Top-end external SSDs with USB 3.2 Gen 2×2 interface can deliver blazing fast writes up to 1000 MB/s.
In today’s world, external hard drives have become an essential accessory for transporting and backing up data. With the availability of high-capacity drives at affordable prices, external HDDs and SSDs are widely used by professionals and casual users alike. When shopping for an external drive, one of the key specifications to consider is the writing speed. The write speed determines how fast you can transfer files to the external drive. Selecting a drive with suitable write performance ensures smooth data transfers and quick back up of large files.
But what exactly constitutes a good writing speed for an external hard drive? This depends on several factors like the interface type, cache memory, drive RPM for HDDs and flash technology for SSDs. Manufacturers usually specify the sequential read/write speeds for drives, but real-world speeds may vary based on usage patterns. In this article, we will take a look at the key criteria that affect the write speed of external drives and explore examples across various drive types and interfaces. Understanding these details will help you choose an appropriate external hard drive based on your usage – whether you need to dump large volumes of data quickly or occasionally write a few documents.
Key Factors that Influence External Hard Drive Write Speeds
Interface Type
The interface protocol and version used to connect the external drive plays a major role in determining the maximum speeds it can achieve. Some common interfaces seen in external HDDs and SSDs include:
- USB 2.0 – With a maximum bandwidth of 60 MB/s, USB 2.0 interfaces limit most hard drives to real-world sequential write speeds of 25-30 MB/s.
- USB 3.0/USB 3.1 Gen 1 – Offers up to 625MB/s link bandwidth enabling most hard drives to deliver sequential writes around 100-130MB/s.
- USB 3.2 Gen 2 – Doubles the interface bandwidth to 10Gbps or 1250MB/s allowing high performance SSDs to hit writes speeds over 500MB/s.
- USB 3.2 Gen 2×2 – Further doubles the interface bandwidth to 20Gbps enabling bleeding edge external SSDs to hit write speeds approaching 1000MB/s.
- Thunderbolt 3 – Provides massive 40Gbps bandwidth letting high-end external SSDs fully utilize the capabilities of fast flash storage and NVMe interfaces to deliver phenomenal write speeds beyond 2500MB/s.
So in summary, USB 2.0 is very limiting, USB 3.0/3.1 Gen 1 offers decent performance for HDDs, while USB 3.2 Gen 2×2 and Thunderbolt 3 remove interface bottlenecks for cutting edge external SSDs.
Drive Cache
For traditional external hard disk drives (HDDs), the amount of cache memory also affects sustained write speeds. More cache helps buffer write operations so that data can be collectively written to disk later. Typical cache sizes are 32MB or 64MB for entry level drives, and 128MB or 256MB for high performance models. As a rule of thumb, doubling the cache typically increases real-world write speeds by around 10-20%. So an HDD with 256MB cache may sustain write speeds around 110MB/s compared to 90MB/s for a 128MB cache drive. Beyond 256MB, returns are diminishing and write speeds improve only marginally.
Disk Rotation Speed (RPM)
This affects the continuous write performance of traditional HDDs. Common rotation speeds are 5400 RPM and 7200 RPM:
- 5400 RPM HDDs – Offer lower performance and are usually found in portable external hard drives. Maximum sequential writes typically top out around 100-120MB/s.
- 7200 RPM HDDs – Offer higher performance thanks to faster rotations and ability to pack more data per platter. Write speeds usually range between 120-180MB/s for high capacity models.
So in summary, 7200 RPM external HDDs can deliver up to 80% faster write speeds compared to 5400 RPM drives. But they consume more power, generate more heat and vibration. Modern 2.5-inch portable HDDs increasingly use 5400 RPM disks to optimize size, thermal performance and energy efficiency.
Flash Memory & Controller
For external solid state drives (SSDs), the quality of NAND flash chips and SSD controller makes a huge difference to write speeds. Main factors include:
- Flash Type – SLC, MLC, TLC, QLC in order of decreasing performance. Modern external SSDs utilize 3D TLC or QLC NAND flash for optimal balance of cost and performance.
- Controller – Determines how efficiently the flash storage is managed. Better controllers like Phison, Silicon Motion and Samsung offer much higher write speeds and IOPS.
- PCIe/NVMe interface – Interface between flash storage and controller. NVMe enables much higher performance compared to SATA interfaces used in older SSDs.
As a result of rapid evolution in flash storage, modern high-end external SSDs with PCIe 3.0 x4 NVMe interfaces can deliver mind-blowing sequential write speeds exceeding 2500MB/s. On the other hand, entry level external SSDs may be limited to 300-400MB/s writes despite using seemingly similar 3D TLC NAND chips.
Typical Write Speeds Examples
Now that we have seen how various drive characteristics impact write performance, let us look at some real-world examples of write speeds you can expect from popular external hard drives available today across various interfaces.
5400 RPM Portable HDDs
These compact 2.5-inch hard drives spinning at 5400 RPM are commonly used in bus-powered portable external HDDs. Models from leading brands include:
- Seagate Backup Plus Slim/Ultra Touch – Up to 120 MB/s
- WD My Passport – Up to 110 MB/s
- LaCie Mobile Drive – Up to 130 MB/s
Thanks to capacities up to 5TB, these portable HDDs offer excellent capacity for backups and file storage. The max sequential write speeds range between 100-130 MB/s which is decent for occasional transfers of large files like photos, videos or project archives.
7200 RPM Desktop HDDs
These 3.5-inch drives spinning at 7200 RPM deliver faster write speeds and are used in desktop external HDDs where portability is less of a concern. Examples include:
- Seagate Backup Plus/Expansion Desktop – Up to 120 MB/s
- WD Elements Desktop – Up to 150 MB/s
- LaCie d2 Professional – Up to 180 MB/s
The high capacities up to 10TB+ along with write speeds in the range of 120-180 MB/s make these suitable for professional creative workloads like photo/video editing and PC gaming recordings.
External SSDs – SATA Interface
External SSDs with a SATA interface can deliver 2-4x faster writes compared to portable HDDs. But peak speeds are limited by the 6Gbps interface bandwidth. Examples include:
- Samsung T5 – Up to 540 MB/s
- SanDisk Extreme Portable SSD – Up to 550 MB/s
- WD My Passport SSD – Up to 515 MB/s
These externals SSDs are capable of sequential write speeds in the range of 400-550 MB/s thanks to the SATA interface. With compact, rugged designs and capacities up to 2TB, these are great for content creators and professionals looking for excellent portable performance.
External SSDs – USB 3.2 Gen 2×2
Cutting edge external SSDs supporting the USB 3.2 Gen 2×2 standard can deliver blazing fast writes rivaling Thunderbolt 3 models. Examples include:
- Samsung X5 – Up to 1000 MB/s
- SanDisk Extreme Pro Portable SSD – Up to 2000 MB/s
- WD Black P50 Game Drive SSD – Up to 2000 MB/s
These external SSDs can max out the USB 3.2 Gen 2×2 interface with real-world sequential write speeds exceeding 1000 MB/s in some cases. The rugged design and compact form factor make these ideal for on-the-go professionals dealing with large files and video content.
External SSDs – Thunderbolt 3
Thunderbolt 3 external SSDs represent the cutting-edge of high performance storage with extremely fast 40Gbps interfaces. Examples include:
- Samsung X5 Thunderbolt 3 SSD – Up to 2800 MB/s
- Seagate FireCuda Thunderbolt 3 SSD – Up to 2500 MB/s
- G-Technology Thunderbolt 3 SSD – Up to 2800 MB/s
These Thunderbolt 3 external SSDs fully leverage the massive bandwidth to deliver blazing fast sequential writes hitting speeds between 2500-2800 MB/s! Ideal for editing 8K videos, 3D rendering, and other extremely demanding creative workloads.
Factors to Consider When Choosing Write Speeds
When choosing an external drive, consider the following factors with regards to write speeds:
1. Usage Patterns
Consider your common usage patterns and file types handled –
- For occasional writes of documents/photos, basic portable HDDs are adequate.
- For frequent large file transfers, higher write speeds make a noticeable difference.
- For video editing and creative workflows, high performance SSDs are recommended.
2. Interface Compatibility
Ensure your PC/laptop ports are compatible –
- USB 2.0 ports limit speeds to around 30MB/s regardless of drive capability.
- USB 3.0 ports required for 100MB/s+ speeds offered by USB3 external SSDs.
- USB-C/Thunderbolt 3 ports required to benefit from Gen 2×2/Thunderbolt SSD performance.
3. Reliability Needs
SSDs tend to be more reliable than portable HDDs in harsh environments due to lack of moving parts. Consider ruggedized solutions if drive will be exposed to drops, vibration or extreme temperatures.
4. Security Features
If data security is important, look for drives with encryption and password protection to safeguard your data.
5. Cost and Capacity Needs
HDDs offer more storage capacity for the money compared to SSDs. Determine the right balance between cost, capacity and performance based on your budget.
Conclusion
In conclusion, there are several factors like interface, cache memory, RPM and flash technology that impact the write speeds of external hard drives. For typical users, USB 3.0 based portable HDDs or SSDs offer a good balance of affordability, capacity and performance. Professionals dealing with large files can benefit from the blazing speeds offered by high-end USB 3.2 Gen 2×2 or Thunderbolt 3 SSDs to optimize their workflows. At the end of the day, choose a drive as per your specific usage, interface compatibility and budgetary needs.