On Mon, Sep 16, 2013 at 7:02 PM, Martin Wilck <mwilck@xxxxxxxx> wrote: > On 09/16/2013 03:47 PM, Francis Moreau wrote: > [...] > >>>>> Wrt loop1[2], I think you interpret the [2] wrongly. It seems to be the >>>>> kernel index of the device somehow. The mdstat parsing code of mdadm >>>>> doesn't look at this number. If you look at >>>>> /sys/class/block/md124/md/dev-loop*/slot, the number should be correct - >>>>> I tried it here. >>>> >>>> Well I think I interpreted the numbers the way it's described here : >>>> >>>> https://raid.wiki.kernel.org/index.php/Mdstat#md_device_line >>> >>> That description is not quite correct. The number in brackets [2] means >>> the index of the disk in the meta data (for DDF, that's the index in the >>> "physical disks" table of the container). That number isn't very >>> meaningful except for the meta data itself. >>> >>> The logical disk index is represented by the "slot" attribute in sysfs. >>> >>> See e.g. >>> http://lxr.missinglinkelectronics.com/linux+*/drivers/md/md.h#L79 >>> >>> The number displayed in /proc/mdstat is "desc_nr", while the number that >>> actually matters is "raid_disk". >> >> Maybe the description in the wiki is correct but there's a bun in the >> kernel which displays the wrong number ? >> >> If "desc_nr" isn't meaningful, I don't see the point to show it in >> /proc/mdstat. > > Well, we could propose to change the value displayed by the kernel. The > question is whether the kernel maintainers would allow that, because it > would change the kernel-userspace API. mdadm itself doesn't look at this > number, but other tools might, so there is some small but non-zero risk > of breaking something somewhere. Well I was assuming that the API was described by: https://raid.wiki.kernel.org/index.php/Mdstat#md_device_line rather than looking at the source code. I haven't found other documentation for a description of /proc/mdstat BTW. Plus the fact that "desc_nr" isn't really meaningful. > > Let's wait what others have to say. > Agreed. Thanks. -- Francis -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
