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installed Mac OS X on SD card - slow

twoodcc

twoodcc

macrumors P6
Original poster
Feb 3, 2005
15,307
26
Right side of wrong
i have a new 15" mbp, and decided to try out installing the OS on a 16 GB SD card, and man it's super slow.

do i just have a cheap card, or is the transfer speed just slow?
 
Probably both ... unless you're using an Extreme IV or the like, the transfer speed is really limited.
 
The fact that it works at all is cool. I would expect it to be slow. Look how slow it is when booting off the Leopard CD. Compared to running out of main memory/cache it will be extremely slow. Even a high speed SD card meant for HD video will be slow if asked to run the OS of a computer.

That said, SD cards have different speed ratings. You would want a high speed card in a video camera that shoots in HD. In a basic digital photo camera you could get by with an inexpensive and slow SD card. So when you buy a Flash card always check that it's speed rating fits your needs.
 
When I am playing with the developer releases, I install OS X on an external firewire. Still slow, but tolerable.

I use a USB flash drive for a redundant backup, man is that slow! But it is nice to have important stuff off-site.
 
OS X over a USB external is a disk grindfest until the operating system is finally loaded. You're going to need some killer SD or flash drive speeds to compete. My Patriot XPorter flash drive hits 17 MB/s writes and that's lightning.

A typical Sandisk Micro will get 7-8 MB/s.
 
twoodcc said:
i have a new 15" mbp, and decided to try out installing the OS on a 16 GB SD card, and man it's super slow.

do i just have a cheap card, or is the transfer speed just slow?
Click to expand...

Your SDHC card is most likely a class 4 card. One thing you can do to help speed things up is use a class 6 card. It won't make a world of difference but when you are doing things like this everything helps.
 
Like Shake 'n' Bake says, I would have guessed the SD slot is probably on the same USB bus as the keyboard, trackpad and iSight, and if so it doesn't matter what speed the SD card is, it's not going to be any faster than USB2 can manage. If you wanted to boot off something external you'd be better off using a FW800 drive.

But it is cool you can boot off an SD slot if you need to, it'd be a handy thing to have an emergency bootable back up in such a small format.
 
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