Macs have encryption in hardware in the dma channel for their built-in drives (Intel Macs with T2 and all ARM Macs), so the overhead is negligible on the internal ssd. Macs actually don’t even have unencrypted internal drives anymore. The filevault toggle only affects whether the volume encryption key stored in the secure enclave is itself encrypted or not.
Older Macs and external drives are a different story of course.
Yeah, my SSD can do somewhere around 7GB/s read/write, barely half that with the encryption enabled.
And I have an external USB carry with an NVMe drive which should be perfectly capable of doing the maximum (1GB/s on a USB3.1 port) , but with encryption enabled, it’s struggling to do over 350MB/s
That seems odd. You’d expect that if the cpu is doing the encryption and can do 3GB/s for the internal disk then it can do the same for the external one and be limited by the USB or disk speed of 1 GB/s
If it’s a Mac then it’s not the CPU that’s doing the encryption for the internal drive. Macs have separate hardware for that, the CPU can’t even get the key.
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Macs have encryption in hardware in the dma channel for their built-in drives (Intel Macs with T2 and all ARM Macs), so the overhead is negligible on the internal ssd. Macs actually don’t even have unencrypted internal drives anymore. The filevault toggle only affects whether the volume encryption key stored in the secure enclave is itself encrypted or not.
Older Macs and external drives are a different story of course.
Yeah, my SSD can do somewhere around 7GB/s read/write, barely half that with the encryption enabled.
And I have an external USB carry with an NVMe drive which should be perfectly capable of doing the maximum (1GB/s on a USB3.1 port) , but with encryption enabled, it’s struggling to do over 350MB/s
That seems odd. You’d expect that if the cpu is doing the encryption and can do 3GB/s for the internal disk then it can do the same for the external one and be limited by the USB or disk speed of 1 GB/s
If it’s a Mac then it’s not the CPU that’s doing the encryption for the internal drive. Macs have separate hardware for that, the CPU can’t even get the key.
What machine are you benchmarking on?
The performance hit is not really notable on the Intel machines with a T2 or the new M1 / M2 silicon.
That said, in googling for benchmarks, theres not really much to find.
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