by Tim Standing, Vice President of Software Engineering, OWC Holdings Inc.

December 1, 2017

Although we are hard at work on SoftRAID version 6 (which will support APFS) we’re still creating maintenance releases of our currently shipping version, SoftRAID version 5. And one feature we really wanted to add to the next SoftRAID version 5 release was the reporting of the TBW (Total Bytes Written) value for SSDs.

What is the TBW and why does it matter?

The TBW measures how many bytes have been written to an SSD since it left the factory. You can think of the TBW like a car’s ‘odometer’, logging SSD disk usage instead of miles. A car’s odometer grows with every mile driven, while the TBW steadily increases with every byte written to the SSD.

The reason this value matters is that some SSD manufacturers are now including a maximum TBW value in the their warranty terms. For instance, Samsung now warranties all their SSDs either for a certain number of years, or for a maximum number of terabytes written, whichever comes first.

We wanted to make it easy for users to see the Total Bytes Written value for their SSD.

This is just like the warranty for your car which might be 3 years or 36,000 miles, which ever comes first. If you’ve only owned your car for 25 months but have driven 45,000 miles, you can no longer get repairs under warranty. Likewise, if your SSD stops working after you’ve had it for only a couple of months, you won’t be able to replace it under warranty if you’ve exceeded the permissable number of bytes written. How would you even know how many bytes that is without having access to the TBW value?

We wanted to make it easy for users to see the TBW value for the SSDs they were using, so they could better manage SSD usage and keep below the manufacturer’s threshold for warranty coverage. So, for the latest release version of SoftRAID 5 (5.6.4), we’ve introduced code to retrieve and display the TBW for SSDs, making it easy to track your SSD usage.

We need your help!

The way each SSD reports this data is different for each manufacturer; sometimes it even alters between different models from the same manufacturer! Since it’s hard for us to know how every single model of every SSD from every manufacturer does its reporting, we’re asking SoftRAID users to help us get the data we need to calculate the TBW numbers accurately for different models of SSD. We want to make this feature as reliable as possible for everyone, no matter what SSD they are using.

Help us calculate TBW numbers accurately for different SSDs

If you expand the disk tile of an SSD while running SoftRAID version 5.6.4, you’ll see the TBW for your SSD with the label “total bytes written”.

If the SoftRAID application does not show this information it means we’re not able to accurately report TBW data for the particular SSD you are using. If this happens, please let us know and we’ll work with you to get the data necessary to add support for your brand of SSD.

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