When shopping for a Solid State Drive or SSD, you will surely come across a term called TBW. Represents the endurance level of an SSD. Here’s why it’s important and how you can understand it.
SSD Endurance Metric
TBW, or “Terabytes Written,” is a metric that tells you how much data you can cumulatively write to an SSD over its lifetime. As the name suggests, this metric is given in the number of terabytes. So, for example, if an SSD is 350TBW, it can write a total of 350TB before needing to be replaced. In general, TBW gives you an idea of the endurance of a solid state drive.
In particular, TBW is sometimes also referred to as Total Bytes Written, as several enterprise-grade SSDs are now rated TBW in petabytes.
RELATED: What is a Solid State Drive (SSD) and do I need one?
Why is TBW important?
The TBW number is important for SSDs because they have a finite life. SSDs store data in flash memory cells. And although reading data from these cells does not affect them, they degrade every time they are deleted and written. Eventually the flash memory cell is so degraded that it fails. So TBW essentially tells you how much data you can write before the memory cells become unreliable.
The TBW rating is higher for higher capacity drives as they have more flash memory cells to write to. For example, a typical 500 GB SSD has a TBW of around 300, while 1 TB SSDs typically have 600 TBW. Also, enterprise-grade SSDs have a higher TBW than consumer-grade SSDs. However, there are premium consumer SSDs that come with a much higher TBW than typical SSDs.
Should you worry about TBW?
Although TBW is a reliable indicator of an SSD’s endurance, most regular computer users will never reach TBW during the normal lifespan of a drive. So unless you’re writing hundreds of gigabytes of critical data each day, you don’t have to worry about TBW. Also, TBW is important mainly for internal SSDs, as external SSDs are mainly used for data backup and are not written as frequently as internal SSDs. That said, higher endurance is a plus if you’re shopping for a new SSD.
SSDs with a higher TBW rating typically cost more than SSDs with a lower rating. So it’s a good idea to take a balanced approach because if you choose too low a resistance, you can run into problems in the long run. For example, the Adata XPG SX8200 Pro, which is one of our top internal SSD recommendations, offers a great combination of price and TBW.
Best internal M.2 SSD
XPG SX8200 Pro
The XPG SX8200 Pro is probably one of the best PCIe 3 SSDs you’ll find, especially given its 640TBW for the 1TB model and its excellent price per GB.
What is DWPD?
DWPD, or Drive Writes Per Day, is another term used to describe SSD endurance. However, as its name suggests, it indicates how many times you can overwrite the full size of an SSD daily during a specified warranty period. So, for example, if your 1TB SSD is rated 1 DWPD, it can handle 1TB of data written every day during the warranty period. But if your DWPD is 10, it can support 10TB of data written daily.
DWPD is more commonly used in the enterprise space, while TBW is typical for consumer-grade SSDs. Fortunately, if you want to find out the DWPD of an SSD, you can calculate it using the TBW.
To convert TBW to DWPD, use the following formula:
DWPD = TBW / (365 * Warranty (Years) * Capacity (TB) )
How to check the TBW of an SSD
The TBW rating is usually mentioned on an SSD’s data sheet or specifications. Alternatively, you can contact the SSD manufacturer for this information. The TBW of a drive can range from as little as 30 TBW for some SSDs to several thousand TBW for others. While a higher TBW indicates higher resistance, a lower TBW indicates poor resistance.
RELATED: 6 things not to do with solid state drives
How to check the remaining TBW of an SSD
If you are curious about the remaining lifespan of an SSD, you can look up the total amount of data written to it and then compare it to the TBW of the SSD. The official software that ships with the SSD usually displays this information in its SMART (Self-Monitoring, Analysis and Reporting Technology) function.
You’ll need to look for something like “Data Drives Written” or “Total Host Writes”. Depending on SSD usage, this number could be in gigabytes or terabytes. You can convert it to terabytes for each comparison to the TBW. So, for example, if your SSD’s total “Data Drives Written” is 101 TB and its TBW is 300, then the SSD has about two-thirds of its life left.
In addition to the official SSD software, you can also use CrystalDiskInfo on Windows or DriveDX on Mac to find the total data written to your SSD. While CrystalDiskInfo is free to download, DriveDX is paid software, but it comes with a 15-day free trial.
What happens after an SSD crosses its TBW?
Once an SSD crosses its TBW, it’s not completely useless or dead. You can still read the stored information, but you may have trouble writing more data. However, SSDs generally outperform on the TBW front because manufacturers are fairly conservative in assigning TBW ratings.
That said, once the SSD’s SMART function determines that there are no more writable blocks on the SSD or that it is about to fail, it will lock the drive in read-only mode. In this mode, you can no longer write data, but you will be able to read the stored information and transfer it to another SSD or HDD.