Re: patch for partmap probing on RAID/LVM

[Centurion Computer Technology (2005) Ltd]

On Mon, 2007-05-28 at 03:49 +0100, Sam Morris wrote:
> Here's the beginning of a patch for grub-probe itself to make it handle
> RAID/LVM more intelligently. This will work for the most common
> use-cases; the comments describe an idea to make the probing process
> recursive to handle more interesting situations such as LVM-on-RAID.

I assume this isn't complete or working yet.

By the way I don't think that LVM on LVM is actually supported by LVM
itself,
and raid on LVM is an unlikely scenario.


> 
>         diff --git a/util/grub-probe.c b/util/grub-probe.c
>         index 29d0d0a..8e10986 100644
>         --- a/util/grub-probe.c
>         +++ b/util/grub-probe.c
>         @@ -118,8 +118,36 @@ probe (const char *path)
>          
>            if (print == PRINT_PARTMAP)
>              {
>         -      if (dev->disk->partition == NULL)
>         -        grub_util_error ("Cannot detect partition map for %s", 
> drive_name);
>         +      if (dev->disk->partition == NULL) {
>         +        /* If the device does not have a partition map, it may still 
> be a
>         +           RAID or LVM device. */
>         +        /* What happens for LVM-on-RAID, or RAID-on-LVM, or nested 
> LVM?
>         +           Maybe this should be recursive, e.g.:
>         +
>         +           Where (md0) consists of two devices: a whole disk and a 
> pc partition:
>         +            probe_partmap (md0)
>         +             probe_partmap (hd0) -> raid
>         +             probe_partmap (hd1,1) -> raid
>         +              probe_partmap (hd1) -> pc
>         +
>         +          Where (foo-bar) is an LVM Logical Volume on a RAID array 
> on disks using
>         +          gpt partitions:
>         +            probe_partmap (foo-bar)
>         +             probe_partmap (md0) -> lvm
>         +              probe_partmap (hd0,1)
>         +               probe_partmap (hd0) -> gpt
>         +              probe_partmap (hd1,1)
>         +               probe_partmap (hd1) -> gpt
>         +        */
>         +        if (drive_name[0] == 'm' && drive_name[1] == 'd')
>         +          printf ("pc gpt raid\n");
>         +        else if (strchr (drive_name, '-') != NULL)
>         +          printf ("pc gpt lvm\n");
>         +        else
>         +          grub_util_error ("Cannot detect partition map for %s", 
> drive_name);
>         +
>         +        goto end;
>         +      }
>          
>                if (strcmp (dev->disk->partition->partmap->name, 
> "amiga_partition_map") == 0)
>                  printf ("amiga\n");
> 
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-- 
Daniel Reurich

Centurion Computer Technology (2005) Limited.
Ph: 021 797 722