PDA

View Full Version : Filevault 2 I/O performance?




appletechpro
Jul 9, 2012, 09:36 AM
So I got excited to upgrade from a 128 GB RealSSD --> 256 GB Samsung 830.

The drive is running the latest firmware, and I am running a fully updated version of OS X Lion.

I ran the Black Magic disk speed test to get a feel for the new performance, and unfortunately I was only seeing my writes top out at 340 MB/s.

Another thread on here had people speaking of ~ 390 MB/s writes.

Could this be due to Filevault 2 being enabled on my SSD?

My SSD is in the primary SATA III port.



whiteonline
Jul 11, 2012, 04:30 PM
Probably. With any encryption, there is overhead. However, I'd really doubt someone saying he can really tell the difference between 390 and 340 in real world, normal usage.

Now stop benchmarking your SSD; it's the greatest source of wear on NAND these days...

appletechpro
Jul 13, 2012, 01:31 PM
Probably. With any encryption, there is overhead. However, I'd really doubt someone saying he can really tell the difference between 390 and 340 in real world, normal usage.

Now stop benchmarking your SSD; it's the greatest source of wear on NAND these days...

I understand that encryption results in overhead. I also understand that one cannot really tell any practical difference between 340 MB/s and 390 MB/s. Lastly, I definitely understand that writing large files to your SSD isn't doing one any favors.

Actually, my question was more along the lines of -- can I REALLY expect a 50 MB/s performance drop in writes by simply using FileVault 2? Because when you see others with the same drive, same SSD firmware, same OS and same base system getting 50 MB/s faster writes, then one cannot help but wonder about the encryption overhead.

maflynn
Jul 13, 2012, 02:13 PM
anandtech has some stuff on this topic in their Lion Review found here: http://www.anandtech.com/show/4485/back-to-the-mac-os-x-107-lion-review/18

cristian.ny95
Jul 13, 2012, 02:15 PM
Hey, If anyone is using FileVault 2 on Lion can you tell me if you are having performance issues. I had it turned on and even watching a TV show on Netflix caused the fans to run very loud. I just turned it off and i am not seeing any of this happen and my battery seems to be better.

Weaselboy
Jul 13, 2012, 02:20 PM
There is normally a small hit in disk performance as can be seen in this test (http://www.anandtech.com/show/4485/back-to-the-mac-os-x-107-lion-review/18) from Anandtech, but I have never seem anything like what you are describing.

A had FV2 enabled on my early 2011 Macbook Pro and now my 2012 Macbook Air 13" and never saw this.

cristian.ny95
Jul 13, 2012, 02:23 PM
There is normally a small hit in disk performance as can be seen in this test (http://www.anandtech.com/show/4485/back-to-the-mac-os-x-107-lion-review/18) from Anandtech, but I have never seem anything like what you are describing.

A had FV2 enabled on my early 2011 Macbook Pro and now my 2012 Macbook Air 13" and never saw this.

Thanks for your response, Also with turning off FileVault i wiped my SSD in my air and installed a fresh copy of lion just in time for mountain lion, so that might contribute to my performance increase as well.

Weaselboy
Jul 13, 2012, 02:24 PM
Actually, my question was more along the lines of -- can I REALLY expect a 50 MB/s performance drop in writes by simply using FileVault 2? Because when you see others with the same drive, same SSD firmware, same OS and same base system getting 50 MB/s faster writes, then one cannot help but wonder about the encryption overhead.

Some of the tests in the Anandtech article maflynn and I linked do show up to a 50MB/s drop, so yes, it is possible that is the source of your speed drop.

I have been using FV2, and like you said that small a speed drop is not noticeable. I sure can't tell the difference. For my purposes, having full disk encryption is certainly worth the tradeoff.

dyn
Jul 14, 2012, 07:47 AM
My MBA 13" 2012 has the Apple SSD SM256E in it which is simply a 256GB Samsung 830. I have enabled FV2 as well and tested it with the Black Magic app and I got this:

https://img.skitch.com/20120708-mm3rntwp32b6gdfje9ihnty2ja.jpg
Additional runs are somewhere around those figures as well.

appletechpro
Jul 14, 2012, 10:54 AM
anandtech has some stuff on this topic in their Lion Review found here: http://www.anandtech.com/show/4485/back-to-the-mac-os-x-107-lion-review/18

Thanks for this.