[el chupacabra]

I don't know what its really called but I call it virtual memory when OSX decides to use my disk space for ram.

I really hate this and would like to turn it off or at least be able to clear the ram without restarting it. See I'm not one of those people that lets 30GB free space sit unused on my puter. I try to use most of it up. Right now on one of my macs I have about 1 gig free space but after my comp has been on a while it eats it all up. I don't care if my computer gets slower I just want it to use the physical ram and clear it as needed when apps quit. I will be happily working on a project with 1gb disk space and then when I go to save it whoooops not enough space.
i.e. There is no excuse for safari to use 500MB RAM.

[Chuckit]

Buy a Macintosh Plus running OS 6. No worries about all this memory management or having 30GB free.

Or you could just accept that this is how it works and buy a decent hard drive. If you want to get really crazy.

[el chupacabra]

Originally Posted by Chuckit

Or you could just accept that this is how it works and buy a decent hard drive. If you want to get really crazy.

Now that sounds like something a windows user would say. What happened to the art of building clean efficient programs that don't take hundreds of megs of memory for simple tasks. If it has the space, OS ten will often take up 5 gigs...or maybe its allowing other apps that arn't running to do this. There needs to be an option to turn it off. Options are good.

[Chuckit]

Originally Posted by el chupacabra

What happened to the art of building clean efficient programs that don't take hundreds of megs of memory for simple tasks.

You can try that too if you want. I was trying to go with the more practical solutions, but feel free to aim for that pie in the sky.

[msuper69]

Originally Posted by el chupacabra

../. What happened to the art of building clean efficient programs that don't take hundreds of megs of memory for simple tasks. If it has the space, OS ten will often take up 5 gigs...or maybe its allowing other apps that arn't running to do this. There needs to be an option to turn it off. Options are good.

Anybody who has even a rudimentary understanding of how OS X manages memory is laughing as they read your posts in this thread. If your way of memory management is better than what 30+ years of Unix development has come up with, maybe you should contact Apple and offer to fix their OS for them.

[tooki]

Yep. What you know about memory management from Mac OS 9 does not apply to Mac OS X.

In OS X, you don't turn off VM, plain and simply. And note that just because so-and-so-much VM has been allocated does NOT mean it is being consumed on-disk.

Besides, it's terrible practice to run your disk to full (though 1-2GB free should be enough, generally speaking).

tooki

[CharlesS]

You could disable VM by commenting out the lines that start the VM system in /etc/rc. Just don't be surprised when nothing works right after you do this...

[Big Mac]

Originally Posted by el chupacabra

Now that sounds like something a windows user would say. What happened to the art of building clean efficient programs that don't take hundreds of megs of memory for simple tasks. If it has the space, OS ten will often take up 5 gigs...or maybe its allowing other apps that arn't running to do this. There needs to be an option to turn it off. Options are good.

You don't understand how memory allocation works in OS X and other modern operating systems. If you were to read up on it you would realize there's no reason to get uptight over the way your Mac is running. If you have an interest in memory allocation, the real figures to look at are the ones for "real memory" and how the memory pie graph is divided. Many users see huge virtual memory numbers and become distraught over them for no reason whatsoever.

[OAW]

Originally Posted by el chupacabra

See I'm not one of those people that lets 30GB free space sit unused on my puter. I try to use most of it up. Right now on one of my macs I have about 1 gig free space but after my comp has been on a while it eats it all up.

This, my friend, is the root of the problem. You simply are asking for trouble when you operate a modern computer with 1 GB of free space on the disk. The bottom line is that you can't turn VM off. It is a fundamental part of the OS. Period. Dot. End of sentence. What you can do is invest in a larger hard drive .... internal or external ... doesn't matter. But you simply have to have several gigs of free space available. It doesn't have to be 30 ... but it can't be 1 or 2. I would suggest 5 GB of free space minimum.

OAW

[CharlesS]

Originally Posted by OAW

This, my friend, is the root of the problem. You simply are asking for trouble when you operate a modern computer with 1 GB of free space on the disk. The bottom line is that you can't turn VM off. It is a fundamental part of the OS. Period. Dot. End of sentence. What you can do is invest in a larger hard drive .... internal or external ... doesn't matter. But you simply have to have several gigs of free space available. It doesn't have to be 30 ... but it can't be 1 or 2. I would suggest 5 GB of free space minimum.

OAW

This is true. I have witnessed first-hand the carnage of overlapped files that can occur when a drive is kept full all the time...

[moonmonkey]

hard disk space is cheap, Ram and time are expensive.

Get another hard disk and all your problems will disappear (computer problems anyway).

[Big Mac]

Originally Posted by CharlesS

This is true. I have witnessed first-hand the carnage of overlapped files that can occur when a drive is kept full all the time...

You've seen this on OS X? People have referred to certain minor anomalies occurring in low disk space situations, but I've never heard of anything too significant happening. I know running out of disk space is not a prudent thing, but I also know I have been operating my iBook in that condition with nary a problem. I've freed up at least a gig lately, but I used to routinely get low disk space warnings and simply dismiss them each time. Fsck often finds orphaned temp files if I run it, but that's ostensibly the extent of it.

[chabig]

Originally Posted by el chupacabra

If it has the space, OS ten will often take up 5 gigs..

I guarantee that OS X is not taking 5GB of disk space. You can check it out by using terminal to check out the size of /private/var/vm/ It's more likely using 1-1.5 GB.

Chris

[tooki]

Yep. My Activity Monitor shows the VM size as 9.18GB. In fact, there are five VM files on the disk: 64MB, 64MB, 128MB, 256MB and 512MB large, respectively, totaling exactly 1GB. That's the same as my physical RAM. A totally reasonable amount.

tooki

[el chupacabra]

Originally Posted by moonmonkey

hard disk space is cheap, Ram and time are expensive.

Get another hard disk and all your problems will disappear (computer problems anyway).

It seems to be a pain for some of my older imacs.
Correct me if im wrong but firewire 800 drives won't plug into my 400 ports. I haven't come accross any 400 drives recently that weren't outragesly priced.

It just seemed resonable that os x would have an easy way to clear a program's memory when the program quits. It doesn't seem resonable for small programs to keep taking up 500 MB of ram when it isn't even running. Oh well.

Originally Posted by msuper69

Anybody who has even a rudimentary understanding of how OS X manages memory is laughing as they read your posts in this thread. If your way of memory management is better than what 30+ years of Unix development has come up with, maybe you should contact Apple and offer to fix their OS for them.

I didn't clame to have a "rudimentary understanding of how OS X managess memory". Most people don't and will use space to the max, so whats so funny smarty pants. It may work just fine with plenty of disk space, but I'm just annoyed with it because its doesn't manage memory well at all when your disk usage is up there. This isn't windows...I expect more from OS X...

[Chuckit]

You can expect whatever you like. As long as the reality is different, you can either live with it or live unhappily.

[tooki]

Originally Posted by el chupacabra

1. It seems to be a pain for some of my older imacs.
Correct me if im wrong but firewire 800 drives won't plug into my 400 ports. I haven't come accross any 400 drives recently that weren't outragesly priced.

2. It just seemed resonable that os x would have an easy way to clear a program's memory when the program quits. It doesn't seem resonable for small programs to keep taking up 500 MB of ram when it isn't even running. Oh well.

3. I didn't clame to have a "rudimentary understanding of how OS X managess memory". Most people don't and will use space to the max, so whats so funny smarty pants. It may work just fine with plenty of disk space, but I'm just annoyed with it because its doesn't manage memory well at all when your disk usage is up there. This isn't windows...I expect more from OS X...

1. Most FW800 drives work just fine on FW400 computers, with the appropriate cable (which is normally included). That said, FW400 drives are everywhere, vastly more common than FW800 models. Any big box store will carry FW400 drives, and typically the prices have been normal. I got my 300GB 7200RPM Seagate external FW400/USB2 drive for under $200 many months ago. Hardly "outrageous".

2. It clears memory as it is necessary to clear it. Programs these days use the services of many parts of the OS ("libraries"). It's the libraries that use a huge part of the RAM, and since the same library may get reused later by the same app if you relaunch it, or another one, the OS doesn't clear that RAM until it is needed for something else. It's stupid to have RAM sitting empty when it can be put to good use to make things faster.

3. That's right. You have no understanding of Mac OS X's memory management (like most users). And you shouldn't need to have any knowledge of it. But despite this, you seem to think that you know better than the OS how it should be managing memory. Believe me, none of us here do. The engineers who designed this system over a couple of decades pretty much perfected it and took into consideration factors that go far beyond what we'd even think to consider.

Generally speaking, this is a case of a little knowledge being far worse than none at all. Without understanding what the RAM usage statistics mean, you've gotten yourself into a tizzy, when in fact, there's nothing to worry about.

Just leave a gigabyte or two of your disk free and you'll be fine. Fragmentation may cause performance to drop when the disk is full, but that's the case with any disk, regardless of whether VM is running on it or not.

tooki

P.S. You'd better bring your tone down a bit. Saying "so whats so funny smarty pants" to another member is unacceptable.

[Chuckit]

Originally Posted by tooki

P.S. You'd better bring your tone down a bit. Saying "so whats so funny smarty pants" to another member is unacceptable.

Unacceptable as in against the rules or unacceptable as in it instills in me a desire to perform a nuclear wedgie on anyone who says it?

[CharlesS]

Originally Posted by Big Mac

You've seen this on OS X? People have referred to certain minor anomalies occurring in low disk space situations, but I've never heard of anything too significant happening. I know running out of disk space is not a prudent thing, but I also know I have been operating my iBook in that condition with nary a problem. I've freed up at least a gig lately, but I used to routinely get low disk space warnings and simply dismiss them each time. Fsck often finds orphaned temp files if I run it, but that's ostensibly the extent of it.

Yep, I've seen a hard drive with tons of overlapped files, that had been used seriously to the max (free space measured in megabytes rather than gigabytes). Granted, it was running 10.2, so it didn't have the journaling turned on, but still, it happened. Getting that system up and running again involved letting DiskWarrior run for an inordinate amount of time, deleting a ton of files, and doing an Archive and Install. And, of course, since the hard disk had been plagued by overlapped files, a lot of files on the hard drive were damaged. Anyway, it's been my general understanding for years that HFS and HFS+ have a much higher risk of corruption when the disk is nearly full. So don't do this!

[loki74]

Originally Posted by tooki

Yep. My Activity Monitor shows the VM size as 9.18GB. In fact, there are five VM files on the disk: 64MB, 64MB, 128MB, 256MB and 512MB large, respectively, totaling exactly 1GB. That's the same as my physical RAM. A totally reasonable amount.

tooki

I found this thread interesting because I really don't know how memory management in OSX works. When I read your post, it made me curious, how far could I push my VM?

So I did this:
2x Firefox windows
13x Photoshop windows (12 are 150x176px, 1 is 1476x1000px)
iTunes
iChat (Buddy List + 5 IM windows)
Lightwave Modeler (2 objects open; one is 1472 polys, the other is 63368 polys)
Lightwave Layout (720x480px render in progress; scene with 14 objects and 174810 polys)

all running smoothly, using expose smoothly, working and stuff in each, etc etc...and the VM didnt go above 8.47 GB. I was tempted to throw in FCP and Motion, but decided not to; didn't want to push it too much.

It seemed to be using the same amount before I ran all that stuff. So does the amount of stuff youre doing really have all that much of an effect on how much VM you use? It seems to me that if Safari is using 500MB of ram, surely the list above would force it into more?

Or is it simply that the 8.47 GB was allocated, but not necessarily used, and I would have to push it even more to force it to use all that space?

===========

Replying to the OP:

You're right, this isn't windows, its OSX and it should be able to manage memory better than Windows. Thing is, it does. So I'm not sure what your point is. I don't even want to imagine what would happen to my old PC if I tried doing to it what I just did to my Mac 5 mins ago.

IMO, running up your disk usage like that is taking a risk. No matter what, low disk space means trouble. And we're not even talking about RAM. What about temp files used by various apps? I don't mean to be cold or blunt, but you should have seen this coming. Really, its not OSX's fault, its yours. I know it IS common for Windows zealots to say that its the user's fault, not Windows's fault. But in this case, I think its actually true. You may argue that OSX should to it "better," but AFAIK, OSX does it the best right now. Certainly it does it better than Windows.

So I say, let the developers develop, and things will get better. But for now, we have what we have, and we must adapt to it and make the best of it. It would be nice if we could fill our drives to the brim and not take a hit, but its just not realistic.


..all, IMO.

[JKT]

If you are using older iMacs, then the problem is more likely to be that they only have 4200rpm drives with small disk caches so that when you get paging, the speed of the disk (relatively slow compared to modern drives) and the small size of the cache causes that paging to be slow. If you want to improve the performance, then a newer, faster hard drive in a FW 400 enclosure kit will give you a boost - maybe not a massive one, but significant enough to notice. As others have stated, you really do need to leave at least 2GB of space on your disk. Maxing the RAM wouldn't hurt either.

Personally, I can quite regularly get 2GB of vm paged to my disk (I know, I need more RAM... just can't afford it at the moment as those 1GB chips just aren't cheap ).

[OreoCookie]

Settle down people.

To the OP: the people here have answered your question: OS X is nothing like OS 9, so you shouldn't turn off virtual memory. If you want to speed up your computer, buy a new harddrive (Firewire 800 drives work fine with the proper cable, although I'm not sure why you claim, you can't get Firewire 400 drives anymore). You can also add new RAM or (from the sound of it) consider a new computer as well.

I also strongly recommend that you free up some disk space, 2-3 GB should be available at all times.

[osxrules]

Originally Posted by tooki

Yep. What you know about memory management from Mac OS 9 does not apply to Mac OS X.

In OS X, you don't turn off VM, plain and simply. And note that just because so-and-so-much VM has been allocated does NOT mean it is being consumed on-disk.

What bugs me about that is why do the apps report that they are using so much if that is not the case? As you will know from my thread about Safari reporting using 2GB+ of virtual memory, it does cause concern especially when the apps report odd amounts because it looks like there is a problem.

It's not that I doubt OS X's memory management as others have said. It's second to none. I've had literally about 2-3 programs open under one Windows account and changed user to find that the system was unusable. I had to switch back to the other user and quit the programs before I could use the machine properly. And that was a brand new modern PC. My brother has an old G3 imac and with OS X, it performs better than Windows on a modern machine. He leaves all sorts of things open and switches users without much slowdown at all.

Originally Posted by CharlesS

Yep, I've seen a hard drive with tons of overlapped files, that had been used seriously to the max (free space measured in megabytes rather than gigabytes). Granted, it was running 10.2, so it didn't have the journaling turned on, but still, it happened. Getting that system up and running again involved letting DiskWarrior run for an inordinate amount of time, deleting a ton of files, and doing an Archive and Install. And, of course, since the hard disk had been plagued by overlapped files, a lot of files on the hard drive were damaged. Anyway, it's been my general understanding for years that HFS and HFS+ have a much higher risk of corruption when the disk is nearly full. So don't do this!

I did that for years without a hitch. I even managed to get my free space down to zero k on quite a few occasions. The OS comes up with a warning saying that it has suspended all disk activity. I didn't know it could overlap files like that .

Why didn't Apple stick with UFS only and get rid of HFS? It still supports resource forks in a way.

[JKT]

Because UFS is completely case sensitive and has its own problems - just imagine the number of applications that would need to be rewritten to use it, never mind the issues that end-users would have with it!

All file systems have their disadvantages as well as their advantages.

[tooki]

Originally Posted by CharlesS

Yep, I've seen a hard drive with tons of overlapped files, that had been used seriously to the max (free space measured in megabytes rather than gigabytes). ... Anyway, it's been my general understanding for years that HFS and HFS+ have a much higher risk of corruption when the disk is nearly full. So don't do this!

In my years of doing Mac service and online support, I've never heard of full disks being the cause of overlapped files. When the disk gets too full Bad Things™ definitely happen, but overlapped files isn't one of them.

Originally Posted by JKT

If you are using older iMacs, then the problem is more likely to be that they only have 4200rpm drives with small disk caches

Hard disk cache size is vastly overrated in IDE drives. Also, all iMacs have had 5400RPM or faster drives. (4200RPM is a speed for notebook drives. Early desktop drives spun at 3600RPM, later ones at 5400RPM, then 7200RPM, and now 10,000 and higher. Intermediate speeds didn't exist.)

Originally Posted by osxrules

1. What bugs me about that is why do the apps report that they are using so much if that is not the case? As you will know from my thread about Safari reporting using 2GB+ of virtual memory, it does cause concern especially when the apps report odd amounts because it looks like there is a problem.
...
2. I did that for years without a hitch. I even managed to get my free space down to zero k on quite a few occasions. The OS comes up with a warning saying that it has suspended all disk activity. I didn't know it could overlap files like that .

3. Why didn't Apple stick with UFS only and get rid of HFS? It still supports resource forks in a way.

1. I'd also like to know what the numbers really all mean, since they clearly don't mean what one would instinctively assume. The best we can do right now is what Apple says: look at the Wired and Active memory as "used" and consider all the rest as free.

2. I don't think that low free space causes overlapped files. It can cause damage to individual files that are open at the time, since they are then unable to be saved.

3. Because UFS a) isn't a Mac format, b) is not as optimized as HFS+ on OS X. c) HFS+ is more capable than UFS, by a great deal. d) UFS is the name used by a smattering of similar -- but not identical or compatible -- formats.

Why is (a) important? Because you don't want to require a reformat in order to install. By making Mac OS X run off of the HFS+ disks that Mac users had been using for years, it meant you could do a simple install, and leave all your files where they are. That's a huge advantage. Also, it means that you can take an OS X disk and put it on a Mac OS 8.1-9.x machine and access the contents. This, too, is hugely important, since adoption of OS X was not a one-time occurrence in the Mac world, but rather a gradual adoption over many years.

(b) Mac OS X performs terribly on UFS volumes. The difference is night and day.

(c) Pretty much the only thing UFS could do out of the starting gate that HFS+ couldn't was case-sensitivity. But that's now an HFS+ option, though one normally not desirable for everyday use.

(d) Yeah, it's kinda bad when one name refers to many things...

tooki

[JKT]

Originally Posted by tooki

Hard disk cache size is vastly overrated in IDE drives. Also, all iMacs have had 5400RPM or faster drives. (4200RPM is a speed for notebook drives. Early desktop drives spun at 3600RPM, later ones at 5400RPM, then 7200RPM, and now 10,000 and higher. Intermediate speeds didn't exist.)

Even the G3 iMacs? I'll stand corrected, but wouldn't a modern drive via a FW connection be a better performer still?

[CharlesS]

Originally Posted by tooki

In my years of doing Mac service and online support, I've never heard of full disks being the cause of overlapped files. When the disk gets too full Bad Things™ definitely happen, but overlapped files isn't one of them.

It just seems to me that if you have an improper shutdown or some other case where the extents table doesn't get updated properly or a file somehow is written to the wrong place, that wrong place is way more likely to be on top of another file if the disk is nearly full...

At any rate, I've very recently had to deal with a hard disk that was almost completely full, and had a nasty case of overlapped files. Chalk it up to coincidence if you like. But I think we can agree that having the disk almost full like that is not good for the health of the drive, yes?

[wataru]

The bus is generally not the bottleneck for low end drives. A 5400RPM drive is slow no matter how you connect it; the idea is to get a drive with a faster spindle, like 7200RPM.

[tooki]

Originally Posted by JKT

Even the G3 iMacs? I'll stand corrected, but wouldn't a modern drive via a FW connection be a better performer still?

Yep, 3600RPM drives were around in the early 90s at the latest. By 1998, 5400RPM was standard, and 7200 was available on high-end drives, and 10,000RPM on server drives, with 15,000RPM drives right around the corner in 2000.

A FireWire disk is faster, but a faster replacement internal drive is also desirable. (Less CPU overhead.)

tooki

[tooki]

Originally Posted by wataru

The bus is generally not the bottleneck for low end drives. A 5400RPM drive is slow no matter how you connect it; the idea is to get a drive with a faster spindle, like 7200RPM.

Actually, that's not really true, either. The biggest single factor in throughput is areal density, which is primarily a factor of the total capacity of the drive. A faster spindle speed increases throughput somewhat, but spindle speed's primary claim to fame is reducing rotational latency.

It is true that the interface is seldom the bottleneck.

tooki

[tooki]

Originally Posted by CharlesS

It just seems to me that if you have an improper shutdown or some other case where the extents table doesn't get updated properly or a file somehow is written to the wrong place, that wrong place is way more likely to be on top of another file if the disk is nearly full...

At any rate, I've very recently had to deal with a hard disk that was almost completely full, and had a nasty case of overlapped files. Chalk it up to coincidence if you like. But I think we can agree that having the disk almost full like that is not good for the health of the drive, yes?

Absolutely! Bad Things™ indeed.

tooki

[msuper69]

Originally Posted by tooki

...
P.S. You'd better bring your tone down a bit. Saying "so whats so funny smarty pants" to another member is unacceptable.

No problem here. I don't get upset over something as trivial as that.

[wataru]

Originally Posted by tooki

Actually, that's not really true, either. The biggest single factor in throughput is areal density, which is primarily a factor of the total capacity of the drive. A faster spindle speed increases throughput somewhat, but spindle speed's primary claim to fame is reducing rotational latency.

It is true that the interface is seldom the bottleneck.

tooki

I'm sure you're right, but that's kind of beside the point. Density generally isn't a parameter you can choose independently of size. Usually people decide which drive they want first by price, where the biggest factor in that is size, then spindle speed. For a given capacity drive, the only way for a consumer to get better performance is to get one with a higher spindle speed.

[turtle777]

Originally Posted by tooki

P.S. You'd better bring your tone down a bit. Saying "so whats so funny smarty pants" to another member is unacceptable.

That's right. If you want to cuss people out, come on over to the Lounge

-t

[el chupacabra]

Originally Posted by msuper69

No problem here. I don't get upset over something as trivial as that.

Thats good I wasn't trying to upset anyone. I hope twooki was being as sarcastic as I was, because I don't see how that would upset anyone... Its not something I've ever heard anyone older than 8 say..

[tooki]

Originally Posted by wataru

I'm sure you're right, but that's kind of beside the point. Density generally isn't a parameter you can choose independently of size. Usually people decide which drive they want first by price, where the biggest factor in that is size, then spindle speed. For a given capacity drive, the only way for a consumer to get better performance is to get one with a higher spindle speed.

True. My point is that overall capacity will be a far more reliable indicator of overall perfomance than spindle speed. (A 7200RPM 6GB drive will be vastly slower overall than a 5400RPM 300GB drive, for example.)

tooki

[production_coordinator]

I find it funny that el chupacabra said "This isn't windows...I expect more from OS X..."

That's like saying "My BMW isn't a Yugo... I expect my BMW not to use gas"

Windows, BeOS, Linux, many Unix, and OS X use VM. They all have their nuances, but VM is there at the heart of it all.

[TheSpaz]

I love Virtual Memory now-a-days. Back in OS 9... I would always turn it off because the computer would run slower and I always had enough real RAM to make up for having it off. Now that I'm using OS X, I don't even think about Virtual Memory cause everything runs just as smooth with it on (as it should). OS 9 is dead and gone and I think OS X does a wonderful and WAY BETTER way of using RAM and Virtual Memory.

There's my 2 cents.

Say goodbye to this:

[production_coordinator]

Originally Posted by TheSpaz

I love Virtual Memory now-a-days. Back in OS 9... I would always turn it off because the computer would run slower and I always had enough real RAM to make up for having it off. Now that I'm using OS X, I don't even think about Virtual Memory cause everything runs just as smooth with it on (as it should). OS 9 is dead and gone and I think OS X does a wonderful and WAY BETTER way of using RAM and Virtual Memory.

There's my 2 cents.

Say goodbye to this:

The VM in OS 9 wasn't a modern VM. It was a stop-gap hack.

[tooki]

All the memory management in Mac OS 9 was outdated, not just the VM.

tooki

[P]

If you want to try running OS X without virtual memory, use BootCD to make yourself a disc and boot from it. That is how slow it is.

You can find BootCD here:

http://www.charlessoft.com/