443,000 Drives Later: What the Backblaze Reliability Study Actually Tells You to Buy

A peer-reviewed analysis of 443,000 drives and roughly 1.66 million drive-years puts HGST at the top for reliability and Toshiba at the bottom, with Seagate and Toshiba failing at about twice the rate of WD and HGST. Those are strong numbers from a large sample, and they are also among the most misread numbers in storage.

What a fleet average can tell you is which models deserve a shortlist. What it cannot tell you is whether the drive in the post will be the one that fails on a Tuesday with your only copy of a library on it. Both of those things are useful, as long as you keep them apart.

What the numbers measure, and what they do not

The most common mistake is reading the brand ranking as a buying instruction. Brands do not fail; models do. Within a single brand, one model can be among the best in the study and another among the worst, which is why the model number on the label matters more than the logo on the box.

How to choose a drive using it

1. Step 1 Fix the capacity and the budget first

   A 20TB drive at a bargain price is not a bargain if you needed two 10TB drives for redundancy. Decide the layout before the shopping list, because the layout determines how many drives you buy.

2. Step 2 Compare models, not brands

   Take the exact model number from the listing and look for its own rate. A brand-level average tells you about a purchasing department, not about the drive in your basket.

3. Step 3 Check the sample behind a model's rate

   A model with a handful of drive-years can show a dramatic percentage that means very little. Small samples produce big numbers in both directions.

4. Step 4 Test the drive before you trust it

   A full surface scan or a long self-test on a new drive catches the damage that shipping causes. It takes hours, and it is the cheapest insurance in the whole process.

5. Step 5 Plan the replacement before the warranty ends

   Drives are consumables with a service life, not fixtures. Decide now what the next drive will be, so a warning sign becomes a purchase rather than an emergency.

6. Step 6 Keep two copies, one off-site

   Reliability statistics reduce the chance of failure. They do nothing about deletion, ransomware, a power surge or a fire, which is why the second copy is not optional.

What the study cannot see

• USB enclosures and laptop drives, which live in different heat and vibration conditions.
• Shipping damage, which is often what actually kills a new drive within its first month.
• SMR versus CMR recording, which changes rebuild times more than failure rates.
• Power quality, and cheap enclosures with controllers that fail before the disk does.
• Selection bias: a fleet buys particular models, in particular volumes, for its own reasons.
• Your workload - a drive that idles all day is not the same as one recording four cameras.

Is HGST still the brand to buy?

The ranking describes drives sold under that name. The name has largely been folded into Western Digital's line-up since the acquisition, so what you can buy new today is often a different label on a related design. Use the model-level data, not the badge.

Does this mean Toshiba drives are bad?

It means the fleet's Toshiba drives failed at a higher rate on average. A single unit is not a statistic; the point of the data is to shift your prior, not to predict your drive's future.

Is RAID a backup?

No. RAID keeps a system running through a disk failure. It does not protect against deletion, ransomware, a controller fault or a fire, because all of those reach every disk in the array at once.

How long should a backup drive last?

Plan on three to five years of useful service, and replace on evidence - growing reallocated-sector counts, mounting read errors - rather than on a calendar alone.