For backups, an external SSD is the better choice if you want speed, a quiet drive with no moving parts, and a small size, and an external hard drive is the better choice if you want the most capacity for the money. Neither type is a backup strategy on its own, because one drive is a single copy. CISA's guidance is to keep three copies of important files on two kinds of storage with one copy offsite.
This guide compares the two drive types, explains how Time Machine and File History use an external drive, lists what to check before you buy, and gives a short routine for safe backups. Prices and specifications were checked on 2026-10-31.
Who this is for and what you will have at the end
This is for anyone buying an external drive to back up a Windows PC or a Mac, or deciding whether to replace an old one. At the end you will know how much capacity you need, which drive type suits your situation, how to set it up with the built-in tools, and how to avoid the common ways a backup drive fails to protect you.
SSD vs HDD: the short comparison
| Factor | External SSD | External hard drive (HDD) |
|---|---|---|
| Speed | Faster. Microsoft says SSDs are smaller and faster than HDDs | Slower |
| Noise | Noiseless, per Microsoft | Makes some noise while working |
| Moving parts | None | Spinning platters (general design of hard drives) |
| Size and weight | Smaller and lighter | Usually larger |
| Capacity per dollar | Usually lower | Usually higher |
| Best use | Frequent backups, travel, fast restores | Large archives, bulk backups |
Microsoft's storage overview states that SSDs are smaller and faster than HDDs, are noiseless, and are now the most common storage type, while HDDs are more common in older devices. Its page does not cover price, durability or lifespan, so the last three rows above are general characteristics of the two designs, not figures from a single source.
What the speed difference means for backups
The first backup copies everything, so a fast drive finishes sooner. After that, tools such as Time Machine and File History copy only what changed, so the drive's top speed matters less. Samsung's US page for its T7 portable SSD lists up to 1,050 MB/s sequential reads and up to 1,000 MB/s sequential writes over USB 3.2 Gen 2. Those are the maker's peak figures. Real speed depends on your computer's port, the cable and the files.
Durability
An SSD has no moving parts, and Samsung describes its T7 as shock resistant, though its US page gives no numeric drop rating. A hard drive has spinning platters and read heads, which is why it is more sensitive to knocks while it is running. Neither type lasts forever, and a drive that is in a bag every day takes more wear than one in a drawer.
There is no authoritative failure-rate comparison for consumer external drives in the sources used here. Backblaze publishes annual failure-rate statistics, but they describe drives in its own data centers, not portable drives in a backpack, so they should not be used to predict yours. The practical conclusion is simple: assume any single drive can fail, and plan for it with a second copy.
Cost
Prices change often, so check a retailer on the day you buy. As an example, Samsung's US store listed its T7 portable SSD at $274.99 for 1 TB, $479.99 for 2 TB (shown as out of stock) and $1,094.99 for 4 TB on 2026-10-31. Source: Samsung US T7 page. This guide could not verify a current price for a comparable external hard drive from the manufacturer's page, so compare the same capacity at the same retailer before you decide.
When you compare, divide the price by the capacity to get a cost per terabyte. For backups, capacity matters more than top speed, because the drive has to hold your data plus history.
How much capacity do you need?
Apple's Time Machine guidance says to use a drive with roughly twice the storage of your Mac, and to use it only for Time Machine unless you create a separate APFS volume for other files. That rule of thumb is a sensible starting point for Windows as well.
Microsoft's File History page does not state a drive capacity or file system requirement. File History saves your default libraries (Documents, Pictures, Videos and Music), custom libraries, and the Desktop. Add up what those folders hold, then choose a drive several times larger so it can keep earlier versions.
Using the drive with built-in backup tools
Mac: Time Machine
Apple's steps are:
- Connect the drive to your Mac.
- Open System Settings, go to General, then Time Machine.
- Add a backup disk. You can erase the drive, and you can encrypt the backup with a password.
- Keep that password, because you need it to restore encrypted files.
Time Machine makes hourly backups for the past day, daily backups for the past month, and weekly backups for older periods. When the disk fills, the oldest backups are removed. Apple says to eject the drive or shut down the Mac before you unplug it.
Format matters. Apple says Time Machine cannot back up to a disk formatted for Windows. If you connect one, it can be reformatted to a Mac format, which permanently removes everything on it. Apple names APFS as the preferred format for a Time Machine disk, and says Time Machine still supports Mac OS Extended (Journaled). If your Mac runs macOS 27 or later, note Apple's warning that network backup targets that depend on the Apple Filing Protocol, such as an AirPort Time Capsule, are no longer recommended.
Windows: File History
Microsoft's steps are:
- Connect an external drive.
- Open Control Panel, go to System and Security, and select Save backup copies of your files with File History.
- Select Turn on. If the wrong drive is chosen, select Select drive, pick the destination and select OK.
To restore, open File Explorer, right-click the folder that used to contain the file, select Restore previous versions, and pick a version on the Previous Versions tab. Microsoft warns that restoring replaces the current version and cannot be undone, so use Restore to if you want a separate copy.
If File History says your drive has been disconnected for too long, reconnect it and run a backup manually.
Sharing one drive between a Mac and a PC
A single disk cannot serve as a dedicated Time Machine disk and a Windows backup disk. Apple describes exFAT as a Windows-compatible format for volumes over 32 GB, and says Disk Utility does not support NTFS, which a Mac can read but not write. Simplest option: buy one drive per computer, or use a drive for file storage in exFAT and keep Time Machine on a separate Mac-formatted drive.
Safer backup habits
CISA's small-business page calls the 3-2-1 rule a trusted guideline: three copies of important files, on two different types of storage media, with one copy stored offsite, away from your location. It also recommends a backup solution that runs automatically and regularly, and testing that you can restore data fully and partially.
For an external drive at home, that translates to:
- Keep a second copy elsewhere. A cloud backup or a second drive at another location covers fire, theft and flood, which a drive in the same room does not. The related guide iPhone backup: iCloud vs computer and how to restore shows the same idea for phones.
- Do not leave the drive connected. CISA's page on protecting data says to avoid leaving the external drive connected when you are not backing up, because ransomware could reach it and delete or corrupt your backups. Store it in a safe place when not in use.
- Encrypt the backup. CISA notes that encryption prevents unauthorized people from accessing or manipulating your data. Both Time Machine and many drives offer encryption, and you must keep the password.
- Test a restore. Restore a few files now, while nothing is wrong, to confirm the backup is usable.
- Eject before unplugging. Apple says to eject the drive or shut down the Mac before you unplug it. Do the same on Windows with Safely Remove Hardware.
Which should you buy?
| Your situation | Reasonable choice |
|---|---|
| Small laptop backup, travel, fast restores | External SSD |
| Large photo or video archive, bulk storage, tight budget | External hard drive |
| Backup stays in a drawer most of the time | Either, with capacity as the main factor |
| Mac with Time Machine | Either, formatted for Mac, at least about twice your Mac's storage |
| Windows PC with File History | Either, sized well above your libraries and Desktop |
| Data you cannot replace | Two copies, one offsite, whatever the drive type |
If you carry the drive in a bag, the SSD's lack of moving parts is a real advantage. If it sits on a shelf and you want 4 TB or more, a hard drive will usually cost less, though you should confirm that at your retailer. If you are also worried about your laptop's own storage, the guide laptop RAM: 8 GB vs 16 GB covers a related upgrade question.
Checklist
- Work out how much data you have, then pick a drive about twice that size or more.
- Compare cost per terabyte at one retailer on the day you buy.
- Choose an SSD for portability and speed, an HDD for bulk capacity.
- Format the drive for your computer: Mac format for Time Machine, and note Time Machine cannot use a Windows-formatted disk.
- Turn on Time Machine in System Settings, or File History in Control Panel.
- Encrypt the backup and store the password safely.
- Keep a second copy offsite, and unplug the drive when you are not backing up.
- Test a restore.
References
- Microsoft Support, All about SSD, HDD, and storage types
- Microsoft Support, Backup and restore with File History
- Microsoft Support, Reconnect your File History drive in Windows
- Apple Support, Back up your Mac with Time Machine
- Apple Support, Backup disks you can use with Time Machine
- Apple Support, Types of disks you can use with Time Machine on Mac
- CISA, Back Up Business Data
- CISA, How to Protect the Data that is Stored on Your Devices
- Samsung US, Portable SSD T7 1 TB
This guide was researched and drafted with AI assistance and checked against the vendor documentation listed in its References. Read the maintained version and related guides on EpiFive.
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