Peter Staubach wrote: > Hans Reiser wrote: > >>>>> >>>> >>>> Wow. What is all that space used for? Other journalling file >>>> systems that >>>> I have seen have limited things like journals to a much smaller space, >>>> >>> >> BSD FFS has a 10% limit unless you are root. They are correct to do so. >> > > Yes, they reserve that space so that their algorithms to choose blocks > from > the various cylinder groups can continue to choose blocks in decent > locations. > BSD FFS doesn't journal though. > > The SunOS UFS does journal metadata and retains the same 10% limit. > It was > discovered that the journal didn't need to be very big in order to > maximize > performance though. A very small log would do as well as a very large > log.
Journaling, and reserving space for good allocation, are totally different concerns, I don't understand why you guys are conflating them. > > It would be interesting to pick a benchmark which represents some market > that usually deploys reiersfs and then experiment with various aspects of > the file system, including the reserve space. It is easy to do, mostly > just time consuming and requires a fair amount of resources. > > ps > >
