Sunday 14 August 2011

How to maximize the lifespan of an SSD

Solid State Drives or SSDs have become really popular because they are faster than Hard Disk Drives (HDDs). But there is a question mark about the life span of an SSD. There is a limit to how many times you can write to an SSD. That is a generally accepted fact. It’s also generally acknowledged that reading from an SSD does not shorten its lifespan. But what happens when an SSD can no longer be written to? Can you recover your data from it?
Some say that once an SSD reaches its write limit you can still read from it as much as you want i.e. there is no catastrophic loss of data. Others say that SSDs do die completely and you can’t even read from them when they do. There is, however, general agreement about how to maximize the lifespan of an SSD:
  • SSDs are expensive and have a limited number of writes before they degrade. So use an SSD mostly to read from. Use it for your operating system and frequently used programs. Do not use it to store data that is frequently written or changed.
    • Do not use it to store temporary files or your web browser cache. The system page file or swap partition should not be stored on the SSD. The page file is used as virtual memory and gets a lot of writes so moving it off the SSD is important.
    • Use an HDD to store files that are frequently written to like the ones mentioned above.
  • Using an HDD in combination with an SSD is important not only to store temporary files but also to store the bulk of your data. That is use the SSD as an “OS drive” and an HDD as a “data drive”.
  • As an SSD degrades, certain cells can no longer be written to. The SSD compensates for that by using extra cells that are included as part of the drive. When even those extra cells start to degrade it uses free space. So it is better to buy a larger SSD than you need and use only a portion of the space. For example buy a 40GB drive and use only about 20-30GB leaving the rest of the space free.
  • Activate TRIM support. This uses a wear levelling algorithm to ensure that all the flash cells in the drive are written to as equally as possible. That is it tries to ensure that no large block of cells degrades faster than other parts of the drive. Windows 7 and Linux have support for TRIM although you may need to manually enable it or use a utility supplied by the SSD vendor.
These are some of the steps you can take to lengthen the lifespan of your SSD. However, keep in mind that SSDs are still very new. There is almost no data about their long term reliability and performance. So always keep backups!

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