[lvm-devel] [PATCH 25/35] Make vg->mda_copies persistent in on disk vg metadata.

[Zdenek Kabelac]

Dne 22.6.2010 05:05, Dave Wysochanski napsal(a):
> This patch adds the ability to read/write the vg->mda_copies values
> from/to the vg metadata.
>
> If we read the VG metadata and this field does not exist, we set
> mda_copies to the default value of 0.  Later in the code, we use
> this special '0' value to indicate a disable of metadata balancing.
> This should preserve existing LVM behavior and ensure metadata balancing
> can be turned off should the need arise.
>
> Signed-off-by: Dave Wysochanski<dwysocha at redhat.com>
> ---
>   lib/format_text/export.c      |    1 +
>   lib/format_text/import_vsn1.c |    5 +++++
>   2 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/lib/format_text/export.c b/lib/format_text/export.c
> index 5f02b5d..52ae11c 100644
> --- a/lib/format_text/export.c
> +++ b/lib/format_text/export.c
> @@ -397,6 +397,7 @@ static int _print_vg(struct formatter *f, struct volume_group *vg)
>   		outf(f, "allocation_policy = \"%s\"",
>   		     get_alloc_string(vg->alloc));
>   	}
> +	outf(f, "metadata_copies = %u", vg->mda_copies);
>
>   	return 1;


Hmm - so we add a new element to the metadata format with the same version 
number? If the user will update metadata with older tools which do not know 
about this parameter - will he get at least a warning that he will miss some 
information ?

Zdenek