Backblaze Backups in Trouble? Risks & Fixes

Your Backblaze backups might be in trouble if your files are larger than the per-file size limit, your drive isn’t connected for over 30 days, or you’ve hit the restore bandwidth cap. This article explains the real failure points, how to check for them, and what to do before you lose data.

Formula

The calculator estimates how long it takes to download your data from Backblaze, given your internet speed. The formula is:

Restore time (hours) = (Data size in GB × 8) / (Download speed in Mbps × 0.9)

• Data size (GB) – the amount of data you need to restore, in gigabytes.
• Download speed (Mbps) – your internet connection’s download speed in megabits per second.
• 0.9 – a typical efficiency factor (90%) because real-world speeds are lower than the advertised maximum.
• 8 – converts gigabytes to gigabits (1 byte = 8 bits).

The result is in hours. The second output converts that to days.

Worked Example

Using the default values: 500 GB of data, 100 Mbps download speed, over a 30-day window.

1. Convert GB to gigabits: 500 × 8 = 4000 gigabits.
2. Adjust for real-world speed: 100 Mbps × 0.9 = 90 Mbps effective.
3. Divide: 4000 / 90 = 44.44 hours.
4. Convert to days: 44.44 / 24 = 1.85 days.

So restoring 500 GB at 100 Mbps takes about 1.85 days of continuous downloading. If you only have a 30-day window, that’s fine, but if your speed is 10 Mbps, it would take 18.5 days – still within 30 days, but barely. If your data is 2 TB and your speed is 20 Mbps, it would take 92.6 days, which exceeds the 30-day restore window.

Why Backblaze Backups Fail

Backblaze is a popular unlimited cloud backup service, but it has specific limitations that can cause your backups to be incomplete or inaccessible. The most common issues:

• Per-file size limit: Backblaze does not back up files larger than 100 GB (as of 2025). Large video files, database dumps, or virtual machine images over this limit are silently skipped.
• 30-day version history: If you delete a file or your drive is disconnected for more than 30 days, Backblaze permanently removes that file from its servers. You cannot recover it.
• External drive disconnection: If an external drive is not connected for 30 days, Backblaze removes its files from the backup. You must reconnect it regularly.
• Restore bandwidth limits: Free restore is capped at 500 GB per restore (or 1 TB per year for some plans). If you need more, you pay extra or wait.
• Software conflicts: Antivirus, firewalls, or VPNs can block Backblaze’s upload process, causing backups to stall without obvious errors.

How to Check If Your Backup Is Healthy

Don’t wait for a disaster to discover your backup is broken. Here’s a quick check:

1. Open the Backblaze app on your computer. Look at the main window – it shows the last backup date and the number of files.
2. Click “Settings” → “Performance” to see upload speed and pause/resume status.
3. Go to “Settings” → “Exclusions” to see if any large files are excluded.
4. Check the “Issues” tab (if present) – it lists files that failed to upload.
5. Log into your Backblaze web account and browse your file tree. Look for missing folders or files.
6. Test a restore of a few small files to confirm you can actually download them.

If you see “Backup paused” or “Waiting to upload” for more than a few hours, investigate.

Common Problems and Fixes

Here are the most frequent issues users face and how to resolve them:

• Backup stuck at 99%: Often caused by a single large file or a file that’s constantly changing (like a database). Exclude that file or reduce its size.
• External drive not backing up: Ensure the drive is connected and mounted. In Backblaze settings, check that the drive is selected under “External Drives.”
• Files missing after 30 days: If you disconnected a drive or deleted files, they’re gone. You cannot recover them. To avoid this, keep drives connected and don’t delete files until you’re sure you don’t need them.
• Slow upload: Backblaze throttles uploads when you’re using your computer. You can adjust this in Performance settings. Also, check your internet upload speed – if it’s low, the initial backup can take weeks.
• Restore fails: If you’re restoring a large amount of data, the web download may time out. Use the Backblaze Desktop App to restore via the “Restore via Desktop” option, which is more reliable for large restores.

Backblaze vs. Other Backup Services

Backblaze is a continuous, unlimited, low-cost backup service. It differs from competitors in key ways:

• Backblaze vs. Carbonite: Both offer unlimited backup, but Carbonite is more expensive and has similar file size limits. Backblaze’s restore is easier.
• Backblaze vs. IDrive: IDrive offers more control (you can back up multiple computers from one account) but has a 10 GB free tier and paid plans are per-computer. Backblaze is simpler but only one computer per account.
• Backblaze vs. cloud storage (Google Drive, Dropbox): These are sync services, not backup. They mirror deletions and don’t keep version history for long. Backblaze is better for disaster recovery.

Costs and Plans

Backblaze offers unlimited backup for a single computer at a flat annual fee (around $99/year as of 2025). There’s also a two-year plan for less per year. The service includes:

• Unlimited storage and file versions for up to 30 days.
• Free restore via web download up to 500 GB per restore.
• Option to have a physical hard drive shipped to you with your data (for a fee, refundable if you return the drive).

There’s no free tier, but there’s a 15-day free trial. If you need to back up more than one computer, you’ll need separate accounts, which can get expensive.

Alternatives to Backblaze

If Backblaze’s limitations are a deal-breaker, consider these:

• IDrive: Backs up multiple devices, supports file size up to 10 GB (or more with add-ons), and offers 5 TB for ~$80/year. Good for large files.
• Acronis True Image: More expensive but offers full disk imaging and file backup with no size limits. Good for power users.
• Arq (now Arq Backup): Backs up to your own cloud storage (Amazon S3, Wasabi, etc.) – you pay for storage separately. No file size limits, but you manage costs.
• Local backup: An external hard drive with a tool like Macrium Reflect or Time Machine. Not offsite, but fast and free after hardware cost.

Safety Tips for Backblaze Users

To keep your backups safe:

• Keep external drives connected at least once a week to avoid the 30-day removal.
• Check your backup status monthly – set a calendar reminder.
• Exclude large files over 100 GB if you don’t need them, or split them into smaller chunks.
• Use the 30-day version history to your advantage – you can recover from ransomware or accidental edits within 30 days.
• Test a restore at least once a year. A backup you can’t restore is worthless.

Frequently Asked Questions

Does Backblaze back up files larger than 100 GB?

No. Backblaze skips any file over 100 GB. This is a hard limit. If you have such files, you’ll need to compress them, split them, or use a different service.

What happens if my external drive is disconnected for 30 days?

Backblaze marks the drive as “removed” and deletes its files from the backup after 30 days. You’ll get an email warning, but if you don’t reconnect the drive, the data is permanently lost.

Can I restore files that were deleted more than 30 days ago?

No. The 30-day version history means deleted files are only retained for 30 days. After that, they’re gone. This is why you should never rely on Backblaze as the only copy of important files.

How long does an initial backup take?

It depends on your data size and upload speed. For example, 1 TB at 20 Mbps upload takes about 5 days of continuous uploading (1 TB = 8000 Gb, 8000/20 = 400 hours = 16.7 days, but with overhead it’s longer). You can speed it up by adjusting performance settings.

Is Backblaze safe from ransomware?

Yes, to an extent. If your computer is infected, Backblaze will back up the encrypted files. However, because it keeps versions for 30 days, you can restore the pre-encryption versions. But if the ransomware sits for over 30 days, those versions are gone. So act quickly.

Can I use Backblaze for multiple computers?

No. One account covers one computer. If you have multiple computers, you need separate accounts, each with its own fee. There’s no family plan.

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in t | Restore time window | days | 30 | 1 | 365
in s | Data to restore | GB | 500 | 1 | 100000
in b | Internet download speed | Mbps | 100 | 1 | 10000
out time | Estimated restore time | hours | (s * 8) / (b * 0.9) | 1
out days | Time in days | days | ((s * 8) / (b * 0.9)) / 24 | 1