For anything other than the most intensive I/O operations, recent processors will give you very respectable performance.
I don't encrypt whole drives but I do have some AES-encrypted disk images in Snow Leopard, and I get about 38 MB/sec throughput copying (using cp) and 60 MB/sec reading (while also calculating cksum) for files of several hundred megabytes in size. I only have one drive, so the write test includes the time it takes to read the data from the unencrypted hard drive before writing back to the disk image on the same volume. The process that handles the encryption only hits about 30% CPU use while writing and 40% while reading so I assume my hard drive is the limiting factor. If I repeat the read test, so presumably the encrypted data is already cached, it hits over 90 MB/sec throughput and about 60% of a single core is busy. These numbers are for a 2.93 GHz core i7 iMac with the HDS722020ALA330 Hitachi drive. I believe this is the 870 series chip which does _not_ have the new AES instruction set on-chip. -Eric On Aug 18, 2011, at 5:50 PM, William G. Scott wrote: > OS X 10.7 enables you to do whole-drive encryption. > > Here is a description from Arse Technica: > > http://arstechnica.com/apple/reviews/2011/07/mac-os-x-10-7.ars/13 > > I ain't never tried it myself. 10.7 seems to run slow enough as it is. > > -- Bill >
