On Tue, Feb 16, 2010 at 7:27 PM, Weijun Li <weiju...@gmail.com> wrote: > Yes my KeysCachedFraction is already 0.3 but it doesn't relief the disk i/o. > I compacted the data to be a 60GB (took quite a while to finish and it > increased latency as expected) one but doesn't help much either. > > If I set KCF to 1 (meaning to cache all sstable index), how much memory will > it take for 50mil keys?
10/3 what 0.3 takes :) >Is the index a straight key-offset map? I guess key > is 16 bytes and offset is 8 bytes. key length depends on your data, of course. > Will KCF=1 help to reduce disk i/o? depends. w/ trunk you can look at your cache hit rate w/ jconsole to see if increasing it more would help. -Jonathan
