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

[Red Wil <redwil@gmail.com>]

On Wed, 9 Feb 2022 07:02:45 -0600
Roger Heflin <rogerheflin@gmail.com> wrote:

> On Wed, Feb 9, 2022 at 3:12 AM Red Wil <redwil@gmail.com> wrote:
> >
> > 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
> >  
> 
> When I did mine I did a combination of 3 and 2.  I bought new disks
> that were 2x the size of the devices in the original array, and
> partitioned those new disks with partition the correct size for the
> old array.  I used 2 of new disks to remove 2 disks that were not
> behaving, and I used another new disk to replace a 3rd original device
> that was behaving just fine.  I used the 3rd device I replaced to add
> to the 3 new disk partitions and created a 4 disk raid6 (3 new + 1
> old/replaced device) and rearranged a subset of files from the
> original array to its own mount point on the new array.

Obviously, as usual in 'nix' world there are multiple solutions for
the same problem especially if you have a small number of drives.

My real question was regarding (4) if a exact copy bit-wise replica of
an entire disk/spindle would have any technical or safety concerns.

Thanks
Red