root backup-reformat-restore

root backup-reformat-restore

[Marcus Sundman]

The FAQ says that "the best solution for small devices (under about 16 
GB) is to reformat the FS with the --mixed option to mkfs.btrfs".

OK. Does anyone have any good suggestions for doing that with an 
existing / partition (which has special files and whatnot)?

I assume a backup-restore cycle is needed, but with which program(s)?

Thanks!

Re: root backup-reformat-restore

[Hugo Mills]

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On Fri, Nov 18, 2016 at 02:38:25AM +0200, Marcus Sundman wrote:
> The FAQ says that "the best solution for small devices (under about
> 16 GB) is to reformat the FS with the --mixed option to mkfs.btrfs".
> 
> OK. Does anyone have any good suggestions for doing that with an
> existing / partition (which has special files and whatnot)?
> 
> I assume a backup-restore cycle is needed, but with which program(s)?

 - If you don't have (or don't care about) any snapshots, then
    - if you can mount both the old and the new FS at the same time
       - mv
    - else, if you want to replace the old FS with the new
       - tar to a file elsewhere, and untar later
 - else, if you care about the snapshots
    - if you don't care about continuing btrfs send/receive backups to
      somewhere else
      - btrfs send/receive with -c (*)
    - if you want to continue using btrfs send -p incremental backups after
      the migration
       - cry, because you can't

(*) For subvols S1, S2, S3, ...: btrfs send S1; btrfs send -c S1 S2;
    btrfs send -c S1 -c S2 S3; btrfs send -c S1 -c S2 -c S3 S4; etc...

   Hugo.

-- 
Hugo Mills             | Great films about cricket: The Umpire Strikes Back
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
PGP: E2AB1DE4          |

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Re: root backup-reformat-restore

[Marcus Sundman]

On 18.11.2016 02:52, Hugo Mills wrote:
> On Fri, Nov 18, 2016 at 02:38:25AM +0200, Marcus Sundman wrote:
>> The FAQ says that "the best solution for small devices (under about
>> 16 GB) is to reformat the FS with the --mixed option to mkfs.btrfs".
>>
>> OK. Does anyone have any good suggestions for doing that with an
>> existing / partition (which has special files and whatnot)?
>>
>> I assume a backup-restore cycle is needed, but with which program(s)?
>   - If you don't have (or don't care about) any snapshots, then
>      - if you can mount both the old and the new FS at the same time
>         - mv

It's the same partition, so I probably won't have the new FS there at 
the same time.

>      - else, if you want to replace the old FS with the new
>         - tar to a file elsewhere, and untar later

Can tar really preserve all special files' attributes? (I have separate 
partitions for /boot and /home, but the rest is in /)

Thanks!

Re: root backup-reformat-restore

[Hugo Mills]

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On Fri, Nov 18, 2016 at 04:06:22AM +0200, Marcus Sundman wrote:
> On 18.11.2016 02:52, Hugo Mills wrote:
> >On Fri, Nov 18, 2016 at 02:38:25AM +0200, Marcus Sundman wrote:
> >>The FAQ says that "the best solution for small devices (under about
> >>16 GB) is to reformat the FS with the --mixed option to mkfs.btrfs".
> >>
> >>OK. Does anyone have any good suggestions for doing that with an
> >>existing / partition (which has special files and whatnot)?
> >>
> >>I assume a backup-restore cycle is needed, but with which program(s)?
> >  - If you don't have (or don't care about) any snapshots, then
> >     - if you can mount both the old and the new FS at the same time
> >        - mv
> 
> It's the same partition, so I probably won't have the new FS there
> at the same time.
> 
> >     - else, if you want to replace the old FS with the new
> >        - tar to a file elsewhere, and untar later
> 
> Can tar really preserve all special files' attributes? (I have
> separate partitions for /boot and /home, but the rest is in /)

   Yes, I've used it for moving / to a different machine before. Take
a look through the options and pick all the ones that look like
they're dealing with attributes. :)

   Hugo.

-- 
Hugo Mills             | Anyone who claims their cryptographic protocol is
hugo@... carfax.org.uk | secure is either a genius or a fool. Given the
http://carfax.org.uk/  | genius/fool ratio for our species, the odds aren't
PGP: E2AB1DE4          | good.                                  Bruce Schneier

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