ORIGINALLY PUBLISHED 10th February 2016

Hi All,

I got this question from a customer and thought it was worth a discussion. The short answer is yes you can perform both compression and encryption on data – as long as you do the steps in the correct order.

The problem is that encrypted data is basically uncompressable, so you have to make sure you perform the steps in the correct order.

• Compress then encrypt – this works fine
• Encrypt then compress – this basically results in no compression savings at all
   

Inside both the SVC and the Storwize, we make sure that we perform these operations in the correct order.  The compression happens first and then the encryption.

However if you encrypt in an SVC and then compress in a V7000 (or any other controller) which is behind the SVC then your compression ratio will be very low.  (I wouldn’t recommend doing compression behind SVC – but that’s another blog post by itself)

The same can be true when you have applications that are capable of encrypting or compressing data – just think about which function comes first.

I hope this helps some of you.

Andrew