Re: Raid5 assemble after dual sata port failure

[David Greaves <david@dgreaves.com>]

Chris Eddington wrote:
> Key questions:
> - I assume ddrescue will do a much better job of correcting errors when
> imaging a disk?  My colleague used ghost which is just a copy tool.  I
> don't understand the capabilities of ddrescue on raid partitions that well.
ddrescue should do a *much* better job.
It knows nothing about raid and operates on the underlying device. It retries
bad sectors in a clever manner.


> - fdisk -l reports that all the drives are exactly the same size with
> exactly the same # sectors shown below.  I don't quite follow the
> hpa_resize issue, but it appears the drives don't have hidden HPA
> sectors - I guess?  Note that sdc is the original drive, where sda, sdb,
> and sdd are the imaged drives.
> 
> So what do you recommend to do first?  Should I try xfs_repair on the
> ghost copy,
No
 or just re-copy myself using ddrescue?
Yes.
  Are there special
> settings to ddrescue I should consider to verify/correct potential HPA
> changes?
Ideally just ddrescue the entire device to a file and use loopback.

For the faulty disk then if you have space, make a second copy and xfs_repair
using that. If it fails then you can easily re-image the good disks but it may
not be so easy to re-image the bad one.

David