iMac Fusion Drive perfomance loss with File Vault

[Schwertleite]

Hello,

I got the Retina iMac with a 3TB fusion drive. When I originally used Blackmagic’s speed test I measured a disk speed of around >300 Mb/s write and >600 Mb/s read.

Now I have turned on file vault and I seem to constantly measure a reduced speed of up to 200 Mb/s write and up to 500 Mb/s read, which is effectively a 20%-30% perfomance loss. This is much higher than the usually marginal perfomance loss associated with disk encryption.

Is this to be expected? i.e. that the Fusion Drive algorithms cannot fully cope with File Vault?

Any thoughts are much appreciated.

Thanks:

Schwertleite

 

[Weaselboy]

BlackMagic uses incompressible data for its tests, and FV2 is known to be a little slower with incompressible data. Try another test like Aja and see what you get. But there will be some slight write slowdown with FV.

 

[BobertKennedy]

Hello,

I got the Retina iMac with a 3TB fusion drive. When I originally used Blackmagic’s speed test I measured a disk speed of around >300 Mb/s write and >600 Mb/s read.

Now I have turned on file vault and I seem to constantly measure a reduced speed of up to 200 Mb/s write and up to 500 Mb/s read, which is effectively a 20%-30% perfomance loss. This is much higher than the usually marginal perfomance loss associated with disk encryption.

Is this to be expected? i.e. that the Fusion Drive algorithms cannot fully cope with File Vault?

Any thoughts are much appreciated.

Thanks:

Schwertleite

Slower read/write speeds are the result of file vault encryption/decryption, although there are other factors at play such as the processing power of your CPU. This is normal. See https://en.wikipedia.org/wiki/FileVault#Performance for more details.