On 1/28/07, Beni Cherniavsky <[EMAIL PROTECTED]> wrote:
On 1/27/07, Hadar <[EMAIL PROTECTED]> wrote: > I also want to write a script that lets a user easily mount the various > public mirrors ( e.g debian's, ubuntu's). > So I still wonder - Is it completely legal? The mirrors would not like the > idea of users leeching their bandwidth constantly :) > Legal - sure, it's free software. Nice to the server - certainly not! When a whole OS runs, the same dirs/files are read many times. httpfs says it does no caching (beyond what the kernel does automatically), so it will probably download the same parts again and again, causing much more bandwidth than just downloading the image once.
From my experiments, the kernel caching is working quite good.
For example, running the same application twice showed very good start-up times in the second run, as expected... A desirable enhancment to the cache, that will greatly improve the performance is probably read-ahead. With read-ahead we will pre-fetch files in a greedy fashion so that read latency will improve over the cost of a much higher memory consumption. Because RAM prices are becoming lower, IMHO it is something we can live with... If the BitTorrent FUSE file system (btslave.sf.net) can give adequate
performance, you should use it instead because it provides caching, distributes the bandwidth among many computers and even gives back. I say "if" because I suspect BT's high latency for piece requests will make it horribly unresponsive.
Root distributed filesystem, can be really cool indeed. But though the concept sounds great (scalability), there are problems. As you said, latency is a major problem with BT (Lustre filesystem may perform better) Moreover, do you think current upload speeds of end users will be sufficeint for that? So it's not only latency, but also the throughput. OTOH, once you boot it once, it will
already have the needed files and will be much faster next time.
Are you talking about hard-disk caching? Thanks, Hadar vamosproject.org
