On Thursday 21 July 2011 17:26:33 kashani did opine thusly: > On 7/21/2011 4:53 PM, Grant wrote: > > So swap isn't treated exactly like RAM. It actually has special > > handling in Linux which makes it beneficial to have on almost > > any > > Linux system? According to Alan, things get very bad when a > > Linux system hits swap. How can behavior like this be > > beneficial: > > > > "When a linux machine hits swap, it does so very aggressively, > > there is nothing nice about it at all. The entire machine slows > > to a painstaking crawl for easily a minute at a time while the > > kernel writes pages out to disk, and disk is thousands of times > > slower than RAM. > > > > It gets so bad that you can't even run a shell properly to try > > and see what's going on and kill the actual memory hog." > > > > Also, aren't you likely to wear out your hard disk sooner using > > swap? > > 1. swap is good. Unless you have a good reason, leave it there. You > do not have a good reason to remove it and neither does anyone > else. > > 2. Don't use the swap that you have. It's slow. It is not a > replacement for RAM. > > 3. If you use a little bit of swap, 100-200MB, that's fine. It's > also a sign you need more RAM. > > 4. If you're using all your RAM and a couple of GB of swap, you're > screwed. Avoid this. > > 5. Swap that you never write to or read from never needs to hit the > drives. If you're worried about drive wear, turn off logging.
Excellent summary of swap; says a lot of what I was trying to say but didn't succeed. I might argue with your point #1, but then I would be nit-picking and it's very dependant on circumstance anyway. As in all things IT, YMMV -- alan dot mckinnon at gmail dot com
