RamDisk for OS X???

solrac

solrac

Mac Ninja
You know how in OS 9, you could make a RAM Disk, and run everything in it straight from RAM?

And also, how Steve Jobs mentioned on the G5, with 8 GB of RAM, you could load entire 3D worlds into RAM, etc. etc.

And you get speeds of 40x faster than the disk!

Well..... ahem... how the *$#! do you do that in OS X?

How do you load something up into RAM? I got a whole 1 GB of RAM on my 17 inch PB, how can I utilize it as a disk?

Thanks!
 
Open a document/app, and it's loaded into ram (if you have enough physical ram)
 
Hmmm...
well I found "rambunctious" for OS X... I don't see the benefit of the RAM disk.... how can I do a test to visibly notice the benefit?
 
Create a RAM disk and store some apps on it. It *should* start the apps from RAM a lot faster. Unless the RAM disk is paged out the HD.
 
If you use an app that makes frequent writes to disk a RAMdisk will not only make it faster, but also prolong the life of the hard drive. This has been a topic in SETI discussions since the client makes frequent writes of its work to disk.

Also, making a RAMdisk too big and you're taking away from the OS and other apps.

A better idea is to just leave apps opened but close their main window. Like Mail.app or a web browser, when you close all their windows, it's still sitting in memory (black triangle under the icon) so clicking the icon again opens a new window. Do this with all your apps and you'll notice things opening immediately and no load times. Couple that with the fast sleep/wake states and you'll never be interrupted.
 
Copied this from the man page for hdid:

hdid -nomount ram://<sectors>

will attach a ram disk that can be mounted and used after
being formatted with a newfs utility or Disk Utility.app.
A sector is 512 bytes.

A small shell script to create and mount a ram disk:

#!/bin/sh

NUMSECTORS=128000
mydev=`hdid -nomount ram://$NUMSECTORS`
newfs_hfs $mydev
mkdir /tmp/mymount
mount -t hfs $mydev /tmp/mymount
 
If that is true, then why would SETI@Home write to the hard drive, if it is remained open? If the app is running, won't it use the RAM instead?
 
read Lycander's post again. states that SETI@home writes to the disk a lot (which it does) so a ramdisk should make its operation significatly faster because it would be writing to RAM, instead.
remeber that OS X already does significant amounts of work without writing out to disk (more RAM available generally means better performance) writes to HD are less, and system tends to be more reliable. And you need to have a significant amount of installed RAM, for a RAM disk to be worthwhile. Some can argue that with OS X memory management, use of a RAM disk may not add enough to total system response to make it worthwhile for other than special software that would normally do high amounts of disk I/O without regard to installed RAM, so maybe SETI@Home is a good candidate (which might make that a good test app for RAM disk?)
 
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