[SATLUG] RAID5 Recovery - Reassembly questions

Don Wright satlug at sbcglobal.net
Wed Aug 26 16:19:57 CDT 2009


On Wed, 26 Aug 2009 13:13:38 -0700 (PDT), David Labens
<adlabens at swbell.net> wrote:

>  root at RCH-SERVER:/# ddrescue --no-split /dev/sdc1 /dev/sda1 tblog1
>
>Shouldn't there now be a superblock on /dev/sda1 when I run
>  mdadm --examine /dev/sda1

If the partition sizes are not exactly the same the superblock will not
be in the expected location, which is counted as a certain number of
bytes from the end. The backup copy will need to be restored to the same
place it came from to preserve the magic. That's one of the nuisances
about the default superblock format which is changed in some later
versions, but the tools still assume you want to use the old format
unless you know to ask for one of the newer ones.

From earlier --examine output I see your superblock is Version 00.90.03,
generally called a 0.90 superblock, the default format. So is mine,
because I haven't taken the time to change it once I learned the
difference.  --Don



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