On Wed, 26 Nov 2014 12:38:44 -0600 Travis Williams <travis@xxxxxxxxx> wrote: > Hello all, > > I feel as though I must be missing something that I have had no luck > finding all morning. > > When setting up arrays with spares in a spare-group, I'm having no > luck finding a way to get that information from mdadm or mdstat. This > becomes an issue when trying to write out configs and the like, or > simply trying to get a feel for how arrays are setup on a system. > > Many tutorials/documentation/etc etc list using `mdadm --scan --detail > >> /etc/mdadm/mdadm.conf` as a way to write out the running config for > initialization at reboot. There is never any of the spare-group > information listed in that output. Is there another way to see what > spare-group is included in a currently running array? > > It also isn't listed in `mdadm --scan`, or by `cat /proc/mdstat` > > I've primarily noticed this with Debian 7, with mdadm v3.2.5 - 18th > May 2012. kernel 3.2.0-4. > > When I modify the mdadm.conf myself and add the 'spare-group' setting > myself, the arrays work as expected, but I haven't been able to find a > way to KNOW that they are currently running that way without failing > drives out to see. This nearly burned me after a restart in one > instance that I caught out of dumb luck before anything of value was > lost. > mdadm.conf is the primary location for spare-group information. When "mdadm --monitor" is run, it reads that file and uses that information. If you change the spare-group information in mdadm.conf, it would make sense to restart "mdadm --monitor" so that it uses the updated information. mdadm --scan --detail >> /etc/mdadm.conf was only even meant to be a starting point - a guide. You are still responsible for your mdadm.conf file. NeilBrown
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