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Re: dd for failing discs?
From: |
Bernhard Voelker |
Subject: |
Re: dd for failing discs? |
Date: |
Thu, 13 Feb 2014 00:34:58 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 |
On 02/12/2014 12:47 PM, Bernhard Voelker wrote:
> Thanks, I'll prepare a patch for the docs, then.
Here is a proposal.
Have a nice day,
Berny
>From 7f73ea7a32f731baef49b4e8988f0b3c7618a983 Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <address@hidden>
Date: Thu, 13 Feb 2014 00:32:48 +0100
Subject: [PATCH] doc: add dd example for failing disks
* doc/coreutils.texi (dd invocation): Add an example for how to call
dd to save data from a failing disk. Mention GNU 'ddrescue' as one
of the more specialized tools in such a case.
---
doc/coreutils.texi | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 3269291..e2339f3 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -8927,6 +8927,22 @@ tape=/dev/rmt/0
(dd bs=4k seek=1 count=0 && dd bs=512k) <$tape >$disk
@end example
+@cindex ddrescue
+@cindex disks, failing
+For failing disks, other tools come with a great variety of extra
+functionality to ease the saving of as much data as possible, e.g.
+@uref{http://www.gnu.org/software/ddrescue/, GNU @command{ddrescue}}.
+However, in cases where such a tool is not available or when the administrator
+feels more comfortable with the handling of @command{dd}, calling it with the
+options @samp{iflag=fullblock} to avoid short reads and
@samp{conv=sync,noerror}
+to pad out unreadable parts and to continue on read errors might be
+helpful as well:
+
+@example
+# Rescue data from an (unmounted!) partition of a failing disk.
+dd conv=noerror,sync iflag=fullblock </dev/sda1 > /mnt/rescue.img
+@end example
+
Sending an @samp{INFO} signal to a running @command{dd}
process makes it print I/O statistics to standard error
and then resume copying. In the example below,
--
1.8.4.5