{"id":98069,"date":"2021-05-04T07:58:50","date_gmt":"2021-05-04T14:58:50","guid":{"rendered":"https:\/\/www.backblaze.com\/blog\/?p=98069"},"modified":"2025-12-11T13:01:23","modified_gmt":"2025-12-11T21:01:23","slug":"backblaze-hard-drive-stats-q1-2021","status":"publish","type":"post","link":"https:\/\/www.backblaze.com\/blog\/backblaze-hard-drive-stats-q1-2021\/","title":{"rendered":"Backblaze Drive Stats for Q1 2021"},"content":{"rendered":"

\"Backblaze<\/p>\n

As of March 31, 2021, Backblaze had 175,443 drives spread across four data centers on two continents. Of that number, there were 3,187 boot drives and 172,256 data drives. The boot drives consisted of 1,669 hard drives and 1,518 SSDs. This report will review the quarterly and lifetime failure rates for our data drives, and we\u2019ll compare the failure rates of our HDD and SSD boot drives. Along the way, we\u2019ll share our observations and insights of the data presented, and as always we look forward to your comments below.<\/p>\n

2021 Q1 Hard Drive Failure Rates<\/a><\/strong><\/h2>\n

At the end of March 2021, Backblaze was monitoring 172,256 hard drives used to store data. For our evaluation, we removed from consideration 337 drives which were used for either testing purposes or were drive models for which we did not have at least 60 drives. This leaves us with 171,919 hard drives for the Q1 2021 quarterly report, as shown below.<\/p>\n

\"Backblaze<\/p>\n

Notes and Observations on the Q1 2021 Stats<\/strong><\/h3>\n

The data for all of the drives in our data centers, including the 173 drives not included in the list above, is available for download on the Hard Drive<\/a> Test Data webpage. Uncompressed, there is a little over 68GB of data in 2,900 plus CSV files.<\/p>\n

For those of you who reviewed our 2020 annual report<\/a>, you may notice that the 18TB Seagate drives (model: ST18000NM000J) are not included in this report. This drive model was a customer development unit provided to us for testing purposes and as such should not have been included in the 2020 report tables, as we exclude test drives. This quarter we have correctly categorized that drive model as part our testing cohort and as such that model was not included in this report. Customer development units are mechanically complete, but the firmware is considered non-production and as such the drives are considered test drives.<\/p>\n

Four drive models recorded zero failures during Q1. Two of these models, the Seagate 6TB and the Toshiba 4TB, have an average age of nearly six years, and lifetime annualized failure rates of less than 1%\u2014very impressive over their lifetime. The other two models with zero failures, the Toshiba 16TB and the WDC 16TB, have an average age of 4.1 months and 0.4 months, respectively. For these models, having zero failures is a great start and we\u2019ll see how they perform over time. Two other drive models, the Seagate 16TB and the Toshiba 14TB, get honorable mentions as they had only one failure during the quarter. Given both drives are recent additions to our farm, we\u2019ll continue to keep an eye on them as well.<\/p>\n

The overall annualized failure rate (AFR) of 0.85% for the quarter is the fourth consecutive quarter where the AFR was below 1%, a trend we are very pleased with, especially as we\u2019ve added over 42,000 new hard drives to our farm and migrated another 23,600 drives over the period.<\/p>\n

HDDs Versus SSDs, A First Look<\/strong><\/h2>\n

At Backblaze, we use SSD drives in several places, but we currently do not use them for storing customer data\u2014that remains in the realm of hard disk drives. But one place we have both HDDs and SSDs is as boot drives for our storage servers. In our case, describing these drives as boot drives is a misnomer as this cohort is also used to store log files for system access, diagnostics, and more. In other words, these boot drives are regularly reading, writing, and deleting files in addition to their named function of booting a server at startup.<\/p>\n

A little over two years ago, Backblaze started using SSDs as boot drives. It was about that time we could start getting SSDs that were 200GB or so for less than $50 each, which was our price point for the 500GB hard drives we were buying.<\/p>\n

What we have are two groups of drives, one HDDs and the other SSDs, which have performed the same functions in the same environment over time. The table below compares the failure rates in aggregate for Q1 2021 of our HDD and SSD boot drives.<\/p>\n

\"HDD<\/p>\n

Why didn\u2019t we break these out by model? None of the models by themselves had enough drive days to be statistically relevant. In aggregate, the number of drive days is still on the lower side, but the obvious difference in the AFR between the HDD and SSD boot drives is eye-opening.<\/p>\n

If we look at the lifetime results for the HDD and SSD boot drives, the difference in AFR is less, but still significant.<\/p>\n

\"Lifetime<\/p>\n

SSD Reporting Moving Forward<\/strong><\/h3>\n

One obvious takeaway from these tables is that SSD drives fail less often than HDD drives, at least in this use case. But that ignores one important factor, drive age. If we focus on the age of each of the cohorts, there are potential cracks in our \u201cSSD drives are better\u201d supposition.<\/p>\n