Backblaze offer cloud storage for businesses and consumers alike and have 1,888,910,817,100,587,008 bytes of data storage on 181,464 drives spread across four data centres on two continents. Very helpfully for everyone, they also publish data every 3 months showing how reliable, or not, the hard drives they use are and for the first time this year, their data includes SSDs, which makes for some interesting reading.
No Drive Is 100% Reliable
The headline here is that no drive is 100% reliable and so not having a back strategy is unwise to say the least. Drives will fail, and if you do not have the data backed up your data will be lost. Do not expect data recovery services to be able to recover your data.
Spinning hard drives are fragile devices. The disks inside are made out of glass, which breaks easily, even if you drop them from only a small height. In addition if a drive fails when in use, the chances are that the heads, which normally ‘float ‘ on a cushion of air will come into land unexpectedly onto the disks scratching the magnetic coating that stores the data. Either way, there is no way back from this, your data is gone for good.
Q2 2021 Hard Drive Failure Rates
Back to the data from Backblaze. Most of us are still using ‘spinning rust’ hard drives for archiving and larger storage requirements, although more and more of us are using SSDs for boot drives and media storage, more of which later in this article.
At the end of June 2021, Backblaze was monitoring 178,166 hard drives used to store data. In preparing the latest stats they declared that they removed 231 drives from the data because they were used for testing purposes or as drive models for which they did not have at least 60 drives. This leaves 177,935 hard drives for their Q2 2021 quarterly report, as shown below.
What this data shows is that there is all brands have reliability issues. Even when we look at the 3 drives that had no failures in this second quarter come from 3 different brands, Seagate, HGST and Western Digital. If you are interested you can study the full report. Click on the button below to go to the Backblaze blog article…
Hard Disk Drives (HDDs) Versus Solid State Drives (SSDs)
In their Q1 2021 report, Backblaze took an initial look at comparing their HDD and SSD boot drives, both from the perspective of a single quarter and their lifetime. In that first report of SSDs they stated that a numbers-to-numbers comparison was suspect as each type of drive was at a different point in its life cycle.
The average age of the HDD drives was 49.63 months while the SSDs average age was 12.66 months. They do state that the HDD and SSD boot drives perform the same functions, which include booting the storage servers and performing reads, writes, and deletes of daily log files and other temporary files.
The data comparing HDDs and SSDs for for the last quarter in 2020, suggested that the SSDs where much more reliable than SSDs with an Average Failure Rate for the HHDs of 6.26% compared to 0.79% for SSDs,
As they say they were concerned this wasn’t a fair comparison, so in this quarter’s report, to create a more accurate comparison, they looked at the HDD boot drives that were in use at the end of Q4 2020 and went back in time to see where their average age and cumulative drive days would be similar for the SDDs at the end of Q4 2020. They found that there was a much closer match for the end of Q4 2015.
Let’s start with the HDD boot drives that were active on the Backblaze system in Q4 2020 as they were back in Q4 2015...
Now let’s compare that with the SSD boot drives that were active at the end of Q4 2020...
To summarise, when Backblaze reanalysed the data using the same average drive age, and a similar number of drive days, it shows that the difference in the failure rates between SSDs and HDDs is nearly two times higher for HDD boot drives than the SSD boot drives. That said it isn’t nearly 10 times the failure rate they saw in the Q1 2021 report when they compared the two types of drives at different points in their lifecycle.
Predicting The Future?
SSD and HDD Lifetime AFR by Year
As this chart shows, from the start of 2018 the HDD boot drive failures accelerated. This continued in 2019 and 2020 even as the number of HDD boot drives started to decrease when failed HDD boot drives were replaced with SSD boot drives. As the average age of the HDD boot drive fleet increased, so did the failure rate. This makes sense and is borne out by the data, but rather than provide answers, this data raises a couple of questions…
Will the SSD drives begin failing at higher rates as they get older?
In the future, how will the SSD failure rates compare with what they have observed with the HDD boot drives?
Backblaze will continue to track and report on SSDs versus HDDs based on their extensive data.
In Conclusion
All of this shows that SSDs still fail so just because we are using SSDs now for boot drives and media drives, we should not be complacent about backups. Backing up SSDs is still as necessary as it was with HHDs. What is still uncertain, because SSDs are relatively new, is now their failure rates will change over time. Based on the Backblaze data, it’s too early to say.