>> [dedupditto] allows the administrator to select a threshhold after >> which 2 copies of a block are stored rather than 1. For example, if >> many duplicate blocks exist deduplication would reduce that count to >> just 1; at some threshhold, it becomes desirable to have multiple >> copies to guard against the multiplied effects of the loss of a >> single >> block. The default value is '100'. > > What's the interaction between the zfs "copies" property and > "dedupditto" ? > > (my hope would be that if any filesystem referencing a block has > copies=2 or copies=3 at the time the reference is created, that block > will be dittoed the appropriate number of times if it wasn't already).
That's correct. A block with copies set to N will be always have at least N copies on the system regardless of the number of deduplicated references. Adam -- Adam Leventhal, Fishworks http://blogs.sun.com/ahl
