RE: [MLUG] Re: Swap vs. No swap (Michael)

["McNutt, Justin M." <EMAIL:PROTECTED>]

 

-----Original Message-----

Michael, I am curious about how you break up swap across multiple disk partitions. Sure, I can create as many Linux swap partitions as a drive will allow, but how do I set them up across mult. disks? I like the idea, as the disk upon which my swap currently resides is significantly slower than the rest of my system.
 

/dev/hda2    swap    swap    defaults    0    0

/dev/hdb2    swap    swap    defaults    0    0

/dev/sda1    swap    swap    defaults    0    0

Generally, I agree with the arguments against swap. How many of you do 3-D rendering, though? I would much rather let my machine process overnight with two gigs of swap than to go out and purchase that amount of memory. Some people would scoff and maintain memory is so inexpensive now that I can just go buy a couple of gigs for a few hundred dollars. But I'm poor. Seriously, like, struggling student who's paying for school himself poor. When your entire machine cost less than $160 to put together, a couple of hundred dollars could be a whole new machine! Yes, it would be fast as hell to have everything in physical RAM, but for many, that's a pipe-dream; for example, a lot of third world users are happier than a peach to get their hands on an aging 486 with 4MB of RAM. Good luck getting anything even resembling modern to run on that without using swap (unless you consider Minix modern). I guess my point here is that the technical merits of running a swapless machine are obvious. However, as is often the case, reality necessitates a certain degree of flexibility in respect to the issue. It is my belief that we will not see swap going anywhere for a long time.

Are peaches happy?  They only get eaten once, ever...

 

Yes, the two circumstances you describe are the valid (in my mind) exceptions.  In the rendering case, you simply have a very large job using a very swap-able data set that isn't going to impinge on performance much, and in that case, you're probably running the job on a system where:

 

1)  You are aware that the system is doing the rendering, and are thus not using it for other things, which might send the system into a tailspin;

 

2)  The CPU is the bottleneck - working on the rendering job - not the swapping;

 

Therefore, it's not worth the $$$ to buy the RAM it would take to run the entire job in memory, even if you could afford it.  It's just a waste.

 

The other case is where the $$$ isn't available in the first place.  In that case, well, you've gotta do what you've gotta do, and if you need swap to get the job done, then you need it.

 

What's important to keep in mind, though, is that both of these cases are exceptions.  There are good reasons for these exceptions, but they are exceptions nonetheless.  The ideal case is still not to have swap.  This point is lost on a lot of people.  It's weird how folks have gotten attached to their swap spaces; not because they need them, but I think because they're afraid to do without them...  :-)

 

--J

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