[wplug] dd

[Poyner, Brandon]

Just be certain that the new disk has at least as much storage as the
old disk.  I wouldn't necessarily trust Seagate that an 80 gig disk is
always the same size unless it's the exact same model (even then I would
check).  dd does a byte-for-byte copy and if the new disk is even a
little bit smaller you might end up with a truncated filesystem (if the
old disk has partitions that extend to the end of the disk).

Brandon Poyner
Network Engineer III
CCAC - College Office
412-237-3086
 
-----Original Message-----
From: Brandon Kuczenski [mailto:brandon at 301south.net] 
Sent: Tuesday, February 15, 2005 12:39 AM
To: WPLUG
Subject: [wplug] dd

I've heard a lot of talk about dd on this board and elsewhere.  So I
want 
to ask a few questions I have in 'discussion' format.

It's a two-part question.

Background: I'm running a server which provides useful services to two, 
but potentially many more, people.  It has an IDE hard drive which is 
behaving unreliably.

I bought another 80 GB drive to replace it, but it's not exactly the
same 
model (a Seagate "U-series" 80gb, 5400 rpm hard disc is being replaced
by 
a Seagate "Barracuda" 80gb, 7200 rpm hard disc).  I would like to:

  - boot into single-user mode with both drives installed
  - not mount the drives in question
  - not format or label the new, replacement drive
  - run 'dd id=/dev/hdb od=/dev/hdc -possibly -other -arguments'
  - switch the drives and reboot into happiness.

  (1) Does this seem like a proper and successful use of 'dd'?  And (2)
is 
the answer to that question OS-dependent (neglecting the device names
and 
arguments), or only POSIX dependent?

Thanks,
Brandon

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