09.05.2014 20:08, Leyne, Sean wrote: > >>> I was referring to cases where the disk controller has ignored the engine >> careful write order, by "collapsing" disk sector writes and applying them in >> a >> sequence optimal for the disk but out of order from a FB perspective (Jim's >> comment about micro code optimization). >>> >>> In that case, the end result is a corrupted database. >> >> I understand, the point was that FW=ON does not eliminate this problem >> either, only reduce its possibility. > > I don't agree. > > FW=ON means that the data has been written to disk (let's ignore the case of > the write-back-cache enabled disk controller -- it doesn't change the answer).
Generally, FW=ON only means that the data has been passed to the storage controller. The rest depends on its cache and/or microcode, as Jim has correctly pointed out. We cannot control when and in what order our pages get written to the disk itself. We can feel ourselves more or less safe only if the controller is battery backed. Dmitry ------------------------------------------------------------------------------ Is your legacy SCM system holding you back? Join Perforce May 7 to find out: • 3 signs your SCM is hindering your productivity • Requirements for releasing software faster • Expert tips and advice for migrating your SCM now http://p.sf.net/sfu/perforce Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
