Backblaze Not Backing Up External Drive | Fast Safe Fix

When a backup stalls on an external disk, you want clear steps that get the files moving again. This guide shows the exact checks and fixes that resolve the most common causes on macOS and Windows. You’ll confirm the drive meets Backblaze’s rules, fix selection and permission snags, clear .bzvol mismatches from cloning, and set a cadence so the drive stays protected.

Backblaze Not Backing Up External Drive Reasons And Checks

Quick scan: before deeper changes, run these short checks. They catch most issues in minutes.

1. Attach The Drive Directly — Plug the disk into USB/Thunderbolt on the computer. Skip docks that present the disk as a network share. Network-mounted volumes and NAS do not back up in Computer Backup.
2. Open Backblaze Settings — In the Backblaze app, open Settings and confirm the external disk is selected for backup. If it shows unchecked or missing, add it again.
3. Leave It Online For A Session — Keep the disk attached and awake for several hours so Backblaze can scan and upload the first batch. If you back up several disks, connect them together during a catch-up window.
4. Avoid Time Machine On That Disk — Backblaze skips Time Machine volumes. If the drive is used for Time Machine, consider a separate partition for user data or move Time Machine elsewhere.
5. Look For The Hidden .bzvol — Each backed-up disk has a tiny identifier folder (.bzvol) at the top level. If it’s missing or duplicated from cloning, the client can drop or misidentify the disk.
6. Check Version-History Needs — A disk that stays unplugged beyond the base retention window can disappear from the current view. Extended Version History keeps data for longer gaps.

Backing Up An External Drive With Backblaze Rules That Apply

Know the rules: Backblaze backs up local, directly attached drives that follow a few simple constraints. Understanding these removes guesswork and explains why a drive appears as “not backed up.”

• Direct-Attach Only — USB, Thunderbolt, or FireWire disks are eligible. Network shares, NAS, and remote mounts are excluded from Computer Backup.
• No Time Machine Volumes — To prevent duplication, Backblaze skips any volume that contains Time Machine data. Use a separate partition or a different disk for Time Machine if you want Backblaze to include your files from that hardware.
• .bzvol Identifier — Backblaze writes a hidden .bzvol folder at the root of every selected drive. It identifies that physical disk. A clone that copies this folder can confuse the app because two drives then share the same ID.
• Connection Cadence — Keep the disk attached on a regular rhythm so the client can scan and upload new or changed items. A steady cadence also keeps the drive visible in your backup view.
• Continuous Schedule — The default schedule scans and uploads in the background through the day. Paused schedules or battery-only limits can delay uploads from removable media.

These constraints explain many “why isn’t my external drive backing up?” cases. Apply them first, then move to platform-specific fixes.

Fixes That Work On macOS

Mac privacy controls and disk identifiers are the usual friction points. This section moves through settings in a clean order so you don’t bounce between panels.

1. Grant Full Disk Access — Open System Settings > Privacy & Security, then add the Backblaze app entries (Backblaze, bzbmenu, or bzserv where shown) under Full Disk Access. Restart the app after toggling access.
2. Select The Drive In Backblaze — Open the Backblaze menu, choose Preferences > Settings. Confirm the external disk is checked. If it’s absent, click to add it from the drives list. Let the client rescan.
3. Remove Time Machine From That Volume — If the external disk holds Time Machine data, Backblaze won’t include it. Use System Settings > Time Machine to stop using that disk for Time Machine. Optionally partition the disk so user files sit on a separate volume that Backblaze can back up.
4. Fix A Cloned .bzvol — If you cloned one disk to another and both now show odd status, clean the identifier on the clone so Backblaze assigns a fresh ID:
   • Reveal The Folder — In Finder, press Shift + Command + G, enter /Volumes/YourDriveName/.bzvol, then open it.
   • Trash The Contents — Move the files inside .bzvol to the Trash (leave the folder itself if present), then reconnect the disk. Backblaze will recreate a proper ID.
5. Keep The Disk Awake — During a catch-up session, disable sleep for disks. Many enclosures spin down too quickly. A powered hub can help if the port can’t supply steady power.
6. Run A Multi-Drive Session — If you back up several externals, attach them together for a few hours so the client doesn’t keep waiting on absent volumes when scanning.

Fixes That Work On Windows

On Windows, most stalls come from selection gaps, performance throttles, or long periods with the disk unplugged. The steps below walk through each point.

1. Confirm Drive Selection — Open the Backblaze Control Panel > Settings. On the main pane, ensure the external letter (like E: or G:) is selected for backup. If it’s missing, add it. Click Apply.
2. Use Continuous Schedule — In Schedule, choose Continuous. This lets the client scan and upload without a tight daily window. If you prefer a daily window, keep the drive attached during that time.
3. Lift Aggressive Throttles — In Performance, clear Automatic Threading/Throttle and move the slider toward faster uploads. Raise the backup threads a notch. Avoid adding Wi-Fi networks to the “do not back up” list unless needed.
4. Keep The Disk Attached For A Session — Let the first large batch run for a few hours. If several drives are selected but not connected, attach them together so the scanner doesn’t spend cycles waiting for missing volumes.
5. New ID After Cloning — If you duplicated a disk using cloning software, exclude the hidden .bzvol folder from the clone and let Backblaze rebuild it on the new disk. If the clone already copied it, remove the contents of .bzvol on the clone, then reconnect.

Keep Your External Drive Protected Over Time

Once the backup runs, build a simple rhythm so you don’t hit the same wall again. The aim is steady scanning and predictable visibility of the disk in your account.

• Connect On A Regular Rhythm — Attach all selected external drives and run Backblaze for a few hours at least every two weeks. Longer sessions are even better after major file moves.
• Use Extended Version History If You Unplug For Long Stretches — If you travel or store a disk off-site, add Extended Version History. It retains data beyond the base window so the drive doesn’t drop from view when it’s offline for a while.
• Keep Continuous Schedule Enabled — Continuous scanning catches changes during the day. If you often close the lid, set a nightly window and keep the disk plugged in during that slot.
• Separate Time Machine And User Data — If you want both Time Machine and Backblaze on the same hardware, create two partitions: one for Time Machine, one for files. Select only the user partition in Backblaze.

The steps above ensure the client sees the disk, has permission to read it, and has time to upload the changes. It also keeps you within Backblaze’s rules so the drive stays listed.

Troubleshooting Map For External Drive Backups

Use this table: match your symptom to the likely cause and the fast fix. Keep columns narrow for easy phone reading.

Symptom	Likely Cause	Fast Fix
Drive never appears in Backblaze	Network mount or dock presents a network share	Attach directly via USB/Thunderbolt; select the drive in Settings
Drive shows “not backed up” after an app update	Missing .bzvol identifier; drive was unplugged during update	Reconnect the drive; let Backblaze rebuild .bzvol
Two external drives confuse the app	Cloned disk copied the hidden .bzvol folder	Delete contents of .bzvol on the clone; reconnect to assign a new ID
Disk selected but nothing uploads	Short sessions, sleep, or strict throttles	Use Continuous schedule; keep disk awake; relax throttle and raise threads
External used for Time Machine won’t back up	Time Machine volumes are excluded	Stop using that volume for Time Machine or partition into two volumes
Old external disappears from the web view	Long unplugged gap beyond base retention	Add Extended Version History; reconnect for a long catch-up session
Other selected drives slow scanning	Multiple selected drives are unplugged	Attach all selected externals together during catch-up

Step-By-Step: Proving The Backup Is Healthy

After fixes, confirm that Backblaze sees the disk, queues the right files, and uploads on schedule.

1. Force A Rescan — In the app, click Backup Now or unpause the client. Watch the file count rise. On macOS, keep the lid open and the disk awake.
2. Spot-Check In The Web View — Log in to your Backblaze account and open the backed-up file viewer. Drill into the external volume and confirm recent changes appear with current timestamps.
3. Leave A Long Session — Keep the disk connected for a few hours. Large libraries need time for hashing and upload. If you adjusted performance settings, you should see faster progress during this window.
4. Stress Test With A New Folder — Create a folder on the external drive named _bb-test and drop a few files inside. Within a scan or two, those items should appear online.

Where This Leaves You

At this point the client should see your external disk, selection is set, the drive holds a clean .bzvol ID, and the upload stream runs on a schedule that fits your routine. If Backblaze not backing up external drive still appears as a problem, repeat the selection check, look again for Time Machine on the volume, and inspect the identifier folder after any cloning workflow.

The same phrase, Backblaze not backing up external drive, often comes down to just three steps: attach the disk directly, select it inside Settings, and give the client a long session to run. Add Extended Version History if you unplug for long periods, and you’ll keep the drive present in your account view even when it’s off your desk.