Can a USB flash drive be used as your Windows swap space?

September 7, 2004 11:00 PM

Can a USB flash drive be used as your Windows swap space? What are the positive aspects of a design such as this?
posted by Keyser Soze to Technology (18 answers total)

It's possible in Windows 98 OSR (B/2). In Windows XP, I'm not sure. As far as I'm aware, XP won't let you put anything that's system critical on a removable drive.

There are no positive aspects to doing it anyway, unless your removable storage (and this wouldn't apply to a USB flash drive) was particularly faster than your permanent drives or had a significantly better seek time.

I believe you can set a Photoshop scratch drive to be a removable drive however..
posted by wackybrit at 11:07 PM on September 7, 2004

The problem with solid state devices right now is that they are limited to only I think a thousand or a hundred thousand read and writes, thus repeated use will deteriorate the memory space.

Having said that, there is someone at SPCR who runs Win 98SE off a compact flash card, I can't find that link right now.
posted by riffola at 11:17 PM on September 7, 2004

>Can a USB flash drive be used as your Windows swap space?

Maybe. It'd last... ohhh... maybe 30 minutes before being worn out, though. :-) (Depends on how much you use the machine, I suppose).

Flash memory is usually good to about 100,000 writes. Then it fails.

DirecTV is rumoured to have once released a working hack for their system that would wear out the cards the same way... Heh... It didn't manage to wear them out, though, so take that for what it's worth.
posted by shepd at 11:18 PM on September 7, 2004

This is a really bad idea. Your system will crawl even slower than usual when swap is needed, and you'll very quickly destroy your USB device.
posted by Voivod at 11:21 PM on September 7, 2004

Response by poster: Can anyone provide documentation for the limited lifespan of flash based devices? And why wouldn't a USB 2.0 solid state memory device be faster than a hard disk?
posted by Keyser Soze at 11:46 PM on September 7, 2004

Here's an overview for a flash memory chip, keyser soze.

Note: 100,000 erase cycle per sector typical

Also, those of you using USB for long term backup, note: 20-year data retention typical

(this is because the microcapacitance holding the charge in the SRAM leaks over time...)

For something more "hardcore", try the datasheet.

AMD makes some of the most popular current flash devices, along with Hynix and ST. I am certain they are on the leading edge of maximum write cycles, but you can certainly look elsewhere for other chips.
posted by shepd at 12:00 AM on September 8, 2004

USB 2.0: 480 Mbits/sec = 60 MB/s
Hard drives at Ultra ATA 133: 133 MB/s
Serial ATA I theoretical limit of 1.5Gbits/s = 187.5 MB/s

Just google around for flash memory limited rewrites. Or even think about it -- you're using a semiconductive substrate with a float and control gate on top (um... I think. It's been awhile), each rewrite has a chance of linking the e source and drain. It's gonna happen eventually.
posted by j.edwards at 12:03 AM on September 8, 2004

And why wouldn't a USB 2.0 solid state memory device be faster than a hard disk?

Flash memory isn't RAM, it's waaaay slower. I know Sony Memory Sticks are in the 2.0-2.5MB/s league, and I just found some specs for a 'high speed' CompactFlash card and it said 5.5MB/s read, and 4MB/s write.. which is miles below even a slow modern hard drive.
posted by wackybrit at 12:17 AM on September 8, 2004

Response by poster: Well, there goes my idea to make me millions.
posted by Keyser Soze at 12:22 AM on September 8, 2004

Can it be done? Yes. You'll have to convince the OS it's not removable, but that isn't too hard.

Positive aspects? There are none. It seems like an exceedingly bad idea across the board: it will be not only hideously slow, but you'll chew through write cycles in a day and have to throw out $100 worth of USB thingy.

If you want to try something crazy with swapping to see if it helps, try turning it off. If you have a couple of gigs of memory, you can actually get away with a stunt like that.
posted by majick at 12:39 AM on September 8, 2004

If you want to do it (have a superfast non-mechanical swap), there are a few companies (like Cenatak) that make PCI cards that take RAM and fake a block device. Most take external power (through the PCI endpiece) from a UPS. Neat stuff.
posted by j.edwards at 1:15 AM on September 8, 2004

Also, unless you have some really wacky memory requirements, just dump some money into maxing out the RAM on your computer. I put my iBook up to 768MB and top tells me I've had 284 pageouts in the last 10 hours.. which is less than a megabyte :-) (OS X pages are 4KB) OTOH, I've had 33185 pageins, or 132MB in total.. which spread over 10 hours still isn't taxing anything.
posted by wackybrit at 1:51 AM on September 8, 2004

Advantages: something to talk about
Disadvantages: everything else
posted by yerfatma at 4:07 AM on September 8, 2004

there may be an advantage from a security point of view.
posted by andrew cooke at 6:43 AM on September 8, 2004

A possible not horrible thing to do: Have a USB device, but instead of flash memory, have it contain normal memory. It's meaningless to save swap space between different times anyway. I don't know if it's possible, but it might make sense in some contexts (like the security one andrew pointed out).
posted by skynxnex at 7:45 AM on September 8, 2004

So...what are some other fun cool things to do with a flash drive? I just got one. And it plays mp3s!
posted by mecran01 at 9:49 AM on September 8, 2004

Run Firefox from it!
posted by j.edwards at 1:21 PM on September 8, 2004

Oooooh, that is cool! Never lose your firefox settings or bookmarks.
posted by mecran01 at 1:48 PM on September 8, 2004