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Hi Brian, it looks like there are two possibilities: * if you're not using a ttreecache: you have disabled the readahead by configuring an unknown readahead strategy in the environment * if you're reading from a ttree through a ttreecache: the readahead is disabled Cheers, Lukasz On Thu, Jan 27, 2011 at 4:20 PM, Brian Bockelman <[log in to unmask]> wrote: > Hi, > > I'm opening a file with the following opaque data: > > root://xrootd.unl.edu:1094//store/data/Run2010B/BTau/AOD/Dec4ReReco_v1/0007/B26C2B64-E101-E011-9C89-002481E14F38.root?readaheadsz=32768&cachesz=327680 > > I.e., I would expect the minimal read size is 32KB. However, I see the following read pattern: > > 110127 16:11:34 001 Xrd: Read: Hole in the cache: offs=2673920000, len=55 > 110127 16:11:34 001 Xrd: Read: Hole in the cache: offs=2673920512, len=145 > 110127 16:11:34 001 Xrd: Read: Hole in the cache: offs=2673921024, len=70 > 110127 16:11:34 001 Xrd: Read: Hole in the cache: offs=2673921536, len=154 > 110127 16:11:34 001 Xrd: Read: Hole in the cache: offs=2673922048, len=24 > 110127 16:11:35 001 Xrd: Read: Hole in the cache: offs=2673922560, len=162 > > I would have expected all these reads to be handled by the cache. This is with ROOT 5.27.06b. > > Brian > >