On 05/18/2012 08:00 AM, JR van Rensburg wrote:
On Fri, 2012-05-18 at 00:33 +0200, Charles ELSAESSER WebmailOrange wrote:Due probably to USB local-network addresses order, or perhaps to some other insufficiant USB media management, if your target install media is an USB key, it is farmore better to locate the swap partition on the same physical media.Just beware - usb keys were not designed to take multiple read writes and will eventually fail. So it is not best practice to have a swap on the key Better to have more RAM.
Also, actually using swap, like in the event you have significantly large blobs of data that need to get cached in swap, is *really* slow from USB flash drives. On a system with less RAM than is optimal perhaps this is unavoidable, but USB flash drive reads are way below the speed of a normal SATA disk (low latency but very slow throughput from USB flash VS high latency but huge throughput from HDD); if you thought thrashing was bad on a spinning disk, you can experience a new world of pain with large page sizes with swap a USB flash drive.
That said, on a system with >= 1Gb RAM swap usually isn't necessary (not saying you should do video or raw image processing on a system with just 1Gb RAM, though) and if you tune your USB tiny system the way you would do, say, an advanced SSD setup (/tmp, browser cache and a few other things in tmpfs, no swap, etc.) you could probably squeeze some decent performance out of your setup (other than program data load time/program startup, of course).
Anyway, JRvR's warning about flash writes is very true. If you hit your flash drive hundreds of times with tiny read/write cycles you'll soon have a guitar pick in your hand instead of a flash drive.
