From ceb84598d8c3a166e6949606710771f58eb2be56 Mon Sep 17 00:00:00 2001 From: Jim Meyering Date: Mon, 14 Jun 2010 10:15:57 +0200 Subject: doc: dd: discourage use of very large block sizes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * doc/coreutils.texi (dd invocation): Warn against using a very large block size. Suggested by Imre Péntek. --- doc/coreutils.texi | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'doc') diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 26b4eba64..102ceaf97 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -8020,6 +8020,11 @@ followed by a multiplier: @samp{b}=512, @samp{c}=1, @samp{w}=2, @samp{x@var{m}}=@var{m}, or any of the standard block size suffixes like @samp{k}=1024 (@pxref{Block size}). +Any block size you specify via @samp{bs=}, @samp{ibs=}, @samp{obs=}, @samp{cbs=} +should not be too large---values larger than a few megabytes +are generally wasteful or (as in the gigabyte..exabyte case) downright +counterproductive or error-inducing. + Use different @command{dd} invocations to use different block sizes for skipping and I/O@. For example, the following shell commands copy data in 512 KiB blocks between a disk and a tape, but do not save or restore a -- cgit v1.2.3-70-g09d2