RE: Replacing all disks in a an array as a preventative measure before failing.

[Red Wil <redwil@gmail.com>]

Hello,

It started as the subject said:
 - goal was to replace all 10 disks in a R6
 - context and perceived constraints
   - soft raid (no imsm and or ddl containers) 
   - multiple disk partition. partitions across 10 disks formed R6
   - downtime not an issue
   - minimize the number of commands
   - minimize disks stress
   - reduce the time spent with this process
   - difficult to add 10 spares at once in the rig
   - after a reshape/grow from 6 to 10 disks offset of data in raid
     members was all over the place from cca 10ksect to 200ksect

Approaches/solutions and critique 
 1- add one by one a 'spare' and 'replace' raid member
  critique:
  - seem to me long and tedious process
  - cannot/will not run in parallel
 2- add all the spares at once and perform 'replace' on members
  critique
  - just tedious - lots of cli commands which can be prone to mistakes.
 next ones assume I have all the 'spares' in the rig
 3- create new arrays on spares, fresh fs and copy data.
 4- dd/ddrescue copy each drive to a new one. Advantage can be done one
 by one or in parallel. less commands in the terminal. 

In the end I decided I will use route (3). 
 - flexibility on creation
 - copy only what I need
 - old array is a sort of backup

Question:
Just for my curiosity regarding (4) assuming array is offline:
Besides being not recommended in case of imsm/ddl containers which (as
far as i understood) keep some data on the hardware itself

In case of pure soft raid is anything technical or safety related that
prevents a 'dd' copy of a physical hard drive to act exactly as the
original.

Thanks
Red