Re: How2: use USB key as swap for low mem laptop ^
One of the USB flash memory sticks I use is the SanDisk Micro Cruzer, I have two of them.
They are advertised as 'ReadyBoost Compatible'.
Read speed for an ext2 file system tested at about 5 MBps, and write speed tested at around 27.5 MBps.
Most of the USB's that most people can afford would be about that speed or slower.
Any internal hard disk with an ATA-4 IDE interface or better would beat that.
ATA-4 came out in 1998, so if you computer is less than ten years old you probably will get best performance with your swap area in your hard disk.
ATA-6, ATA-7 and ATA-8 (IDE) hard drives can handle transfer speeds of up to 100 or 133 MBps, but their read and write heads can still only achieve an actual media transfer rate of 60 MBps. The reason they can handle the faster interface is that they cache the data, so if you're writing small files to disk they'll seem faster, but for very large files they're still only about 60 MBps.
A very fast hard drive might get up to 80 MBps, but those would be more expensive than average.
The USB 1.1 interface had low speed transfer rate of only 0.1875 MBps, and the 'full speed USB 1.1 was able to do 1.5 MBps. Both of those are much slower than the slowest hard disk interface, ATA-1, with a transfer speed of 8.33 MBps.
It would be no good having your swap area in one of those, you would be better off with the swap area in the hard disk.
With USB2, we can transfer files at 60 MBps, which is about equal to an ATA-5 capable hard drive, made from around the year 2000 onwards.
Not too many USB devices can read that fast, and they're very much slower to write to, so it wouldn't be sensible to make your swap area in one of those unles you have a particularly fast and high quality flash memory stick.
Not all USB drives are created equal - Computerworld.
Something like an 8GB OCZ ATV Turbo USB Flash Drive might do it, or a Corsair.
Last edited by Herman; October 15th, 2008 at 08:34 PM.
Ubuntu user since 2004 (Warty Warthog)