Hi David, ROOT does not write with a fixed block size. If you write a single object with 100 bytes, ROOT will write 100 bytes. If you fill TTree's you will write the branch buffers with the specified branch buffsize. You can force a very large fixed block size by turning on TFile caching. See TFile::UseCache() where the blocksize will be the specified pagesize (default 512KB). Cheers, Fons. On Sat, 2002-07-20 at 01:37, David R. Relyea wrote: > I have another question, perhaps related to my original question - we're > diagnosing the read/write problems to see what's actually causing the > errors. We have a simple question - what's ROOT's block size for file > I/O? Is it 32k, like gzip? Or something else? I searched but couldn't > find the answer... > > David Relyea -- Org: CERN, European Laboratory for Particle Physics. Mail: 1211 Geneve 23, Switzerland E-Mail: Fons.Rademakers@cern.ch Phone: +41 22 7679248 WWW: http://root.cern.ch/~rdm/ Fax: +41 22 7679480
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