How Long Will my Flash Storage Last?


How long will my Flash drive last? Should I use the 60-minute pause buffer?

This blog post attempts to answer these questions. As you may know from reading our earlier blog post about Flash storage – all Flash is not created equal. Low-cost Flash storage is slower and fails after fewer rewrites. Flash storage vendors try to avoid publishing the rewrite lifetime specification for their devices. 

The ZapperBox offers a convenient 60-minute pause buffer feature. This allows you to rewind live TV for up to 60 minutes at any time. While Flash drives offer portability, durability, and convenience; hard drives outshine Flash when it comes to rewrite lifetime. The ZapperBox offers you a workaround, you can turn off the 60-minute pause buffer. You still get the 5-minute pause buffer, which uses DRAM. 

But can you get away with using the 60-minute pause buffer with your Flash device? A rule of thumb we use is to estimate that a Flash drive should last at least five years under average use.  

Let’s examine the variables we must consider. Below is a table we constructed using an Excel file. You can download a read-only version of this Excel file at this link, save it to your computer and try out your own variations. 

Here are some notes on the above various variables:

  • [ B ] We used 5 GBytes/hour. 1080i HD and 4K HEVC video both require about 5 GBytes/hour of storage.
  • [ E ] Flash drives use wear leveling. New data written is automatically spread across all the empty space. The data for the 60-minute pause buffer is constantly being deleted and rewritten.
  • [ G ] Rewrite lifetime. This is the critical spec that most Flash storage vendors, except SLC Flash vendors, hide. You must search the Internet to get a good estimate. You can estimate it by comparing the write speed of the Flash device against the write speeds in our earlier blog post. Faster Flash devices have higher rewrite lifetime.

 

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