hard drive replacement questions

Tony Baechler tony at baechler.net
Fri Sep 28 11:09:27 UTC 2012

I have to respectfully disagree with you on several of your points.  I'm 
writing from my own experiences having just replaced a bad drive and having 
used Linux for many years now, both on a server and desktop system.

On 9/28/2012 1:59 AM, Henry Yen wrote:
> 2. A command everyone should know is: dmesg
>     That command prints out all of your boot-up messages. The identity
>     of drives will either be in lines beginning with "hda:" "hdb:" (etc.)
>     for IDE drives, and lines containing "Vendor:" and/or "Model:" for
>     scsi/sata drives.

Yes, dmesg is a good idea, but with any newer kernel, it doesn't use the hda 
and hdb syntax at all.  I've found that hdparm is more reliable and gives 
more information.

> 5. Make sure you get a replacement drive that is at least as large as your
>     old drive. You should be able to clone your old drive completely to your
>     new drive using ddrescue or dd-rescue; these cousin commands are based on
>     "dd", but continue on in the face of errors, and use strategies like
>     copying from the end towards the beginning, and in chunks, to absolutely
>     maximize the amount of data copied. After doing that, your new drive
>     will be exactly the same as your old drive (including the logical damage,
>     which will at least no be afflicted with physical error problems), and
>     you should be able to even boot both systems just as before.
>     You can also fsck the new drive, as it won't get confused by
>     hardware failures any more.

While this is generally correct, you're making two wrong assumptions. 
First, that doesn't work on all filesystems.  Specifically, XFS doesn't use 
fsck.  The way to fix an XFS volume is with xfs_repair.  The second problem 
is with Windows.  I promise you that on Windows 2000 and up, and in 
particular with XP, dd and similar won't work.  For the Linux partition, 
ddrescue is great and I would highly recommend it.  I prefer it over dd 
because it does rescue more files and gives a progress report while still 
being fairly fast.  On newer versions of Windows, it won't boot if you do a 
straight dd copy.  You have to change a registry entry first.  I found this 
out when I had an unbootable Windows system after doing a full copy.

> 6. Actually copying the drive could be tricky for you, depending on
>     what hardware you have available. A USB drive converter is the least
>     common denominator, but it's deathly slow. A separate "work space"
>     system on your local network would be better.

If you use Image for Linux or Windows, you can copy to a USB drive or via 
the network.  Depending on how much damage there is, rsync will copy your 
Linux files, but not the boot sectors.  You can also backup to DVDs, but 
that could get complicated.  Image offers good compression.  Unless your 
drive is very full, it probably wouldn't take more than 10 to 15 DVDs at the 
most and almost definitely fewer.

> 7. For future reference, there are various partition cloning/backup
>     systems for Linux that support Linux and Windows partitions, and are
>     very fast (mostly because only blocks that are actually being used are
>     copies, and blocks in the free list are not).

OK, what are they?  They aren't partimage or Clonezilla because I looked at 
both of those.  Clonezilla is very slow and requires booting from a live CD. 
  Partimage is similar.  I didn't find any open source backup programs that 
have as many features as Image for Windows or Image for Linux, are 
completely accessible with screen readers, offer good compression, make 
bootable restore DVDs, can copy to either internal drives, USB drives, DVDs 
or over the network and offer a boot CD with Speakup already included.  If 
you know of any free backup software with that feature set and without a lot 
of bugs, I'm very interested.  Oh, and the Image suite gets updated fairly 
often and frequently gains new features.  Yes, I realize that it's 
commercial, but I really haven't found a free alternative with the same 
features and the same level of accessibility.

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