On Fri, 2011-03-04 at 08:02 +0300, Станислав wrote: > [dd] bs=blocksize doesn't work as expected, for example: > tar -c /somedir | dd bs=256K of=/dev/nst0 > In this example backup record will be recorded to a tape with block size = > 10K instead of 256K because 10K is default for tar. > There is workaround: > tar -c /somedir | dd ibs=256K obs=256K of=/dev/nst0 > If we set block size for input and output separatly - it works as expected.
Even partial block (short read) is a block - especially when you read via pipe. If you want to have only fullblock, dd provides iflag=fullblock for you. See info documentation (or online GNU coreutils manual) for details. > lucid <http://packages.ubuntu.com/lucid/coreutils> (utils): The GNU core > utilities > 7.4-2ubuntu2: amd64 i386 Current version is 8.10, but iflag=fullblock should be present there - added in 7.0
