On Thu, Apr 10, 2008 at 12:13 AM, Michael Rogers <m.rogers at cs.ucl.ac.uk> wrote: > On Apr 9 2008, Daniel Cheng wrote: > >Disk are getting cheaper and cheaper... > >Also, high data redundancy means we can drop any blocks of them without > >problem, right? > > I'm not sure it's that simple - imagine two files with unequal popularity. > If we increase the redundancy of both files, causing some blocks to > dropped, what will happen to the reliability of the two files?
I guess both files are spread over a number of node, and only a small portion would overlap. (just guess, i don't know how freenet really works) Just one popular file can't push another file out. In previous posts, I had proposed to heal *only* a random portion of file of block. This make redundancy grown invert exponentially with popularity.. It's really hard for a single file to had that kind of popularity. > > The only potential problem I have in mind is the LRU drop policy on store > > full. All blocks of an unpopular item may drops around the same time if > > we use this policy.. > > Good point. > > > >I think if the redundancy is high enough, we should use: > > - Random drop old data on store full. > > - LRU drop on Cache full. > >which should give a good balance of data retention and load balancing > > I've recently done some simulations of LRU vs FIFO vs random replacement, > but I haven't had time to write up the results yet. The short version is > that random replacement performs better than LRU or FIFO for some > workloads, and isn't significantly worse for any workload. I didn't > simulate multi-block files or FEC, though. > > Cheers, > Michael > > > _______________________________________________ > Tech mailing list > Tech at freenetproject.org > http://emu.freenetproject.org/cgi-bin/mailman/listinfo/tech >
