You used to be able to boot of a RAM disk... and I believe you still can, if you meet these requirements:
* PowerMac or PowerBook or compatible NOT G3/G4/G5
* Processor upgrades may work
* Mac OS 8.x, probably 9.x, NOT OS X
* Lots of RAM (at least 37MB to spare, which adds up to about 128MB)
* Small OS system folder.
Small system folder... Copy System, Finder, System Resources, PowerPC Enabler (if they're all there), or use Disk Tools image.
This baby should run FAST... and if you copy everything to RAM, boot, drag HD to Trash (seriously!), your PowerBook can run for twice as long on battery!
You used to be able to boot of a RAM disk... and I believe you still can, if you meet these requirements:
* PowerMac or PowerBook or compatible NOT G3/G4/G5
* Processor upgrades may work
* Mac OS 8.x, probably 9.x, NOT OS X
* Lots of RAM (at least 37MB to spare, which adds up to about 128MB)
* Small OS system folder.
Small system folder... Copy System, Finder, System Resources, PowerPC Enabler, Startup Disk CP (if they're all there), or use Disk Tools image.
This baby should run FAST... and if you copy everything to RAM, boot, drag HD to Trash (seriously!), your PowerBook can run for twice as long on battery!
If X could do it, a RAM disk would be useful for some. When recording small bits of video or even large amounts of music a RAM disk can be very helpful. No need to buy a RAID if you're only grabbing 30 seconds of video, or recording a few minutes of audio.
Anyone who says they're worthless doesn't really understand them. A RAM disk that swaps to the drive is virtually useless. A true RAM disk can be very useful.
Sure, RAM disks could be really useful under contrived circumstances like those listed above, but realistically, if you want ram disks in OSX, you don't understand how unix memory management works.
BTW, in linux, I preloaded application icons and desktop pics (as well as apps, if I so desired) with a
cat /usr/share/pixmaps/*.* > /dev/null
on startup. Give that a try if you want <x> to be in ram.
If X could do it, a RAM disk would be useful for some. When recording small bits of video or even large amounts of music a RAM disk can be very helpful. No need to buy a RAID if you're only grabbing 30 seconds of video, or recording a few minutes of audio.
And why doesn't the video recording app offer the possibility to record to a mem buffer (cache) instead of writing everything to the disk if this is so important?
here's a 100 meg ram disk for you:
buf = malloc(100*1024*1024);
(this way, you can just allocate more memory if needed (up to a certain limit, and in the mean time you write as fast as you can to the disk, which means that you can record quite a lot of data even if the rate is faster than what your disk can handle and especially if there are bursts), so your "ram disk" can grow and shrink and doesn't waste real memory)
As already pointed out RAM disk are indeed possible under OS X using some command line tools. I created one once to see if it made any performance improvements as follows: I created a RAM disk, which was all fine and dandy. My, "extensive test", was to copy Mozilla Firebird to it and run it from the RAM disk. I saw no real improvement in performance and promptly got rid of the RAM disk. This may well be due to the high reliance apps have on external frameworks, which are obviously still stored on disk.
Kickaha and Amorph couldn't moderate themselves out of a paper bag. Abdicate responsibility and succumb to idiocy. Two years of letting a member make personal attacks against others, then stepping aside when someone won't put up with it. Not only that but go ahead and shut down my posting priviledges but not the one making the attacks. Not even the common decency to abide by their warning (afer three days of absorbing personal attacks with no mods in sight), just shut my posting down and then say it might happen later if a certian line is crossed. Bullshit flag is flying, I won't abide by lying and coddling of liars who go off-site, create accounts differing in a single letter from my handle with the express purpose to decieve and then claim here that I did it. Everyone be warned, kim kap sol is a lying, deceitful poster.
Now I guess they should have banned me rather than just shut off posting priviledges, because kickaha and Amorph definitely aren't going to like being called to task when they thought they had it all ignored *cough* *cough* I mean under control. Just a couple o' tools.
Don't worry, as soon as my work resetting my posts is done I'll disappear forever.
You know what would be really cool?. The ability to dynamically page into ram, Apps that had aliases in the dock after system start up. That way those particular Apps would load faster in general after a system shutdown/startup and if you could allow the same kind of thing with folders you would get, the ram disk functionality / control that you are all fumbling for ?.
There's one purpose for a RAM disk that noone has mentioned yet : Distributed computing.
If you put all relevant files for for example RC5 onto a RAM disk, then your HD will not keep spinning up!
Until any other process on the machine needs the RAM, and it will be paged out to disk, only to be read back in again later...
It's all the same argument/counter-argument.
Now, what I think you guys *really* mean you want is resident, non-swappable, *wired* memory spaces. Then it would never be written out to disk.
That would take some serious effort... besides, imagine if it *were* available. Every *&%(@#() app would demand that *IT* always have wired memory (Adobe, I'm looking at you...), and screw over everyone else. Then, *wham* we're right back to the days of manually setting how much RAM an app can have. :P No thanks.
The current situation is much nicer, overall. The very few cases where a RAM disk may have a *slight* advantage can be handled in other ways.
You know what would be really cool?. The ability to dynamically page into ram, Apps that had aliases in the dock after system start up. That way those particular Apps would load faster in general after a system shutdown/startup and if you could allow the same kind of thing with folders you would get, the ram disk functionality / control that you are all fumbling for ?.
I have 22 apps in my Dock.
Login would take 10 minutes. :P
Now what *could* be interesting is to maximize the speedup by doing a dependency check on the frameworks needed by each app. If framework Foo is needed by, say, 18 of my 22 apps, then paging that in in the background while Finder loads would likely give *some* boost on the first launch, but none thereafter. A tiny boost. A widdle iddybiddy boost. Naw, not even worth playing with. :P
Until any other process on the machine needs the RAM, and it will be paged out to disk, only to be read back in again later...
I could be wrong but I believe that it is possible to mark something as "ram resident only" so that it is never swapped out to disk. I know that regular Unix-like OSes can do so.
I could be wrong but I believe that it is possible to mark something as "ram resident only" so that it is never swapped out to disk. I know that regular Unix-like OSes can do so.
That's the "wired" memory he was referring to a couple posts up. Long story short: You want absolutely as little wired memory as possible. As is, only a few crucial kernel resources are wired. As Kickaha points out, as soon as you make wired memory an application level resource, you're on a fast train to allocating application RAM in a Get Info window, just like in the bad old days; and you'd have to deal with what happened when someone tried wiring enough memory to exceed real RAM. Not to mention giving the VM system that much less to play with will throttle the system.
The RAM disk just isn't going to happen in OS X. Sure, you can make one, and mount it, and use it, but except for a handful of pathological cases there isn't any point. VM and resource caching both work really well in OS X.
Comments
* PowerMac or PowerBook or compatible NOT G3/G4/G5
* Processor upgrades may work
* Mac OS 8.x, probably 9.x, NOT OS X
* Lots of RAM (at least 37MB to spare, which adds up to about 128MB)
* Small OS system folder.
Small system folder... Copy System, Finder, System Resources, PowerPC Enabler (if they're all there), or use Disk Tools image.
This baby should run FAST... and if you copy everything to RAM, boot, drag HD to Trash (seriously!), your PowerBook can run for twice as long on battery!
* PowerMac or PowerBook or compatible NOT G3/G4/G5
* Processor upgrades may work
* Mac OS 8.x, probably 9.x, NOT OS X
* Lots of RAM (at least 37MB to spare, which adds up to about 128MB)
* Small OS system folder.
Small system folder... Copy System, Finder, System Resources, PowerPC Enabler, Startup Disk CP (if they're all there), or use Disk Tools image.
This baby should run FAST... and if you copy everything to RAM, boot, drag HD to Trash (seriously!), your PowerBook can run for twice as long on battery!
Anyone who says they're worthless doesn't really understand them. A RAM disk that swaps to the drive is virtually useless. A true RAM disk can be very useful.
BTW, in linux, I preloaded application icons and desktop pics (as well as apps, if I so desired) with a
cat /usr/share/pixmaps/*.* > /dev/null
on startup. Give that a try if you want <x> to be in ram.
Originally posted by bunge
If X could do it, a RAM disk would be useful for some. When recording small bits of video or even large amounts of music a RAM disk can be very helpful. No need to buy a RAID if you're only grabbing 30 seconds of video, or recording a few minutes of audio.
And why doesn't the video recording app offer the possibility to record to a mem buffer (cache) instead of writing everything to the disk if this is so important?
here's a 100 meg ram disk for you:
buf = malloc(100*1024*1024);
(this way, you can just allocate more memory if needed (up to a certain limit, and in the mean time you write as fast as you can to the disk, which means that you can record quite a lot of data even if the rate is faster than what your disk can handle and especially if there are bursts), so your "ram disk" can grow and shrink and doesn't waste real memory)
Now I guess they should have banned me rather than just shut off posting priviledges, because kickaha and Amorph definitely aren't going to like being called to task when they thought they had it all ignored *cough* *cough* I mean under control. Just a couple o' tools.
Don't worry, as soon as my work resetting my posts is done I'll disappear forever.
If you put all relevant files for for example RC5 onto a RAM disk, then your HD will not keep spinning up!
Originally posted by iMacfan
There's one purpose for a RAM disk that noone has mentioned yet : Distributed computing.
If you put all relevant files for for example RC5 onto a RAM disk, then your HD will not keep spinning up!
Until any other process on the machine needs the RAM, and it will be paged out to disk, only to be read back in again later...
It's all the same argument/counter-argument.
Now, what I think you guys *really* mean you want is resident, non-swappable, *wired* memory spaces. Then it would never be written out to disk.
That would take some serious effort... besides, imagine if it *were* available. Every *&%(@#() app would demand that *IT* always have wired memory (Adobe, I'm looking at you...), and screw over everyone else. Then, *wham* we're right back to the days of manually setting how much RAM an app can have. :P No thanks.
The current situation is much nicer, overall. The very few cases where a RAM disk may have a *slight* advantage can be handled in other ways.
Originally posted by The Angel of the Abyss
You know what would be really cool?. The ability to dynamically page into ram, Apps that had aliases in the dock after system start up. That way those particular Apps would load faster in general after a system shutdown/startup and if you could allow the same kind of thing with folders you would get, the ram disk functionality / control that you are all fumbling for ?.
I have 22 apps in my Dock.
Login would take 10 minutes. :P
Now what *could* be interesting is to maximize the speedup by doing a dependency check on the frameworks needed by each app. If framework Foo is needed by, say, 18 of my 22 apps, then paging that in in the background while Finder loads would likely give *some* boost on the first launch, but none thereafter. A tiny boost. A widdle iddybiddy boost. Naw, not even worth playing with. :P
Originally posted by Kickaha
Until any other process on the machine needs the RAM, and it will be paged out to disk, only to be read back in again later...
I could be wrong but I believe that it is possible to mark something as "ram resident only" so that it is never swapped out to disk. I know that regular Unix-like OSes can do so.
Originally posted by Agent69
I could be wrong but I believe that it is possible to mark something as "ram resident only" so that it is never swapped out to disk. I know that regular Unix-like OSes can do so.
That's the "wired" memory he was referring to a couple posts up. Long story short: You want absolutely as little wired memory as possible. As is, only a few crucial kernel resources are wired. As Kickaha points out, as soon as you make wired memory an application level resource, you're on a fast train to allocating application RAM in a Get Info window, just like in the bad old days; and you'd have to deal with what happened when someone tried wiring enough memory to exceed real RAM. Not to mention giving the VM system that much less to play with will throttle the system.
The RAM disk just isn't going to happen in OS X. Sure, you can make one, and mount it, and use it, but except for a handful of pathological cases there isn't any point. VM and resource caching both work really well in OS X.