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What are your thoughts on using an SSD with Apple's FileVault hard disk encryption?

  • Will it shorten the lifespan?
  • Will it decrease the read/write performance?
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up vote 3 down vote accepted

Lifespan of the physical disk/drive

FileVault 1

For the home directory, all files written to the SSD will be 8 MB (the default size of bands within a sparse bundle disk image).

Whether writes of those 8 MB bands will cause more or less degradation, than writes without FileVault 1, will depend on factors such as:

  • sizes of files within your home directory
  • how often those files are written
  • and so on

— so for the lifespan part of the question, there can be no one answer for all users of FileVault 1.

FileVault 2

Initial conversion will affect all on-disk bytes. Beyond those initial writes — after conversion is complete — writes with FileVault 2 should have an effect on lifespan no different from writes without.

Read/write performance of both versions of FileVault

In Ask Different:


diskutil(8) Mac OS X Manual Page — expect this to be updated for Mac OS X 10.7 in due course

hdiutil(1) Mac OS X Manual Page

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Thank you, Graham, very informative! – slhck Aug 7 '11 at 22:13
Thank you, I know only a little about SSDs, I think it'll be good to consider a variety of questions and answers … – Graham Perrin Aug 7 '11 at 23:46

It will decrease read/write performance since encryption does cost a little bit of processor time. I would expect less that 10% impact on average.

Lifespan should not be shorter since same amount of data is going to drive regardless of whether it is encrypted or not.

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