Wednesday, June 29, 2011

Further attempts to boot OS X from usb key to EeePC

As I posted yesterday, this looked as if it might be made to work if only I could get its speed of operation up to what it is when I boot Snow Leopard from a external drive.
This will also serve as a test for how well OS X might perform in a multiboot system if installed directly onto the larger ssd.
Yesterday, I considered the possibility that the slowness of my 8GB usb key may have been due to the key being 92% full and I had read that overloading of the usb key may slow it down.
So, today I forked out €40 for a 16GB HP usb key and used SuperDuper, as before to Restore the OS X install that I still have on my external drive.
Again as before, SuperDuper messes up the Chameleon bootloader so when the copy was complete (took a little more than 2 hours) I had to reinstall Chameleon to get the key to boot on my EeePC 901.
In total the boot, to a fully operational desktop took 5 minutes which is not a lot different from the 8GB key that I tried yesterday.
In normal operation on the Desktop, things seemed just a little faster, but still very close to unusable due to its slowness.
The problem seems to be due to very slow write rates for the usb key.
From this specification sheet for the product I bought, read and write speeds are expected at 25 MB/s and 8 MB/s respectively.
However, using the Xbench test, my 8GB key with OS X installed gave about 3.5MB/s for sequential uncached write (suw), and 6 MB/s for sequential uncached read (sur).
For random uncached write (ruw) the speed was an amazingly low 0.2 MB/s while the random uncached read (rur) was around 5 MB/s).
For the 16 GB key I got the following results:
suw=6 MB/s, sur=12 MB/s, ruw=0.3 MB/s and rur=25 MB/s.
For comparison, the external HD that from which I first booted to OS X on the EeePC 901 gave the following results:
suw=17 MB/s, sur=15 MB/s, ruw=12 MB/s and rur=8 MB/s.
Finally, my MacBook (2 GB RAM, 2.26 GHz C2D) gave the following results:
suw=48 MB/s, sur=32 MB/s, ruw=15 MB/s and rur=13 MB/s.
Clearly the biggest difference between the us key readings results from the conventional HDs in the external drive and the MacBook lies in the ruw figures.
In comparison with the conventional drives, the ruw figures for the keys are orders of magnitude less.

So, I don't see any point in persisting with this route and have changed my attention to directly installing Snow Leopard to my new 16 GB usb key together with the new kexts and procedures given in the guide I'm using.
Right now I'm in the process of copying my "first" Snow Leopard to the 16 GB key (this install with then allow me to install my legitimate SL Upgrade without which booting from the external drive to the EeePC did not work.
However, once again writing to the usb key seems very slow. What took about an hour on the external drive looks like it'll need close to four hours on the !6 GB key.
However, the guide does explain the the reason for not installing directly to the netbook ssd is because "I do this because the SSD on the eeepc can be very slow for initial installs".
So, perhaps the slow install may be followed by a reasonably operational system.
I should know tomorrow.

If this doesn't work, I may look at using a very small portable external drive powered only off the usb connection. I saw one today (500 GB) for €60. This is about the size of an iPhone.

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