I've successfully gotten my NAS monitoring program to check the status of my RAID arrays by parsing /proc/mdstat. (Definitely a PITA, but I did get to learn about RAID 10 layouts ans POSIX regular expressions.) I'm now thinking about how to make the program robust in the situation where the array names (in /proc/mdstat) aren't necessarily stable. For example, a couple of arrays might be stopped for some sort of maintenance activity and "swap" names when they are reassembled. The obvious answer is to use mdadm to check the UUIDs of the arrays, but I don't want to do that every time I check the RAID status (currently every 30 seconds). So my plan is to only read the UUID of an array when it first appears in /proc/mdstat (i.e. it wasn't there the last time I read the file). This will work as long as the program notices that an array has been stopped before a (possibly different) array appears with the same name. So it would be nice if there were a simple way to reliably detect that a particular array has been stopped -- even if a different array has since been started with the same name. It appears that I can do this pretty easily with sysfs. >From my initial testing, it looks like I can open each array's array_state file when I first detect the array, and lseek/read will return ENODEV if the array is ever stopped -- even if the array is restarted (with the same or a different name) or if a different array is started with the same name. It seems almost too easy. Is there any reason that this approach won't work? Thanks! -- ======================================================================== Ian Pilcher arequipeno@xxxxxxxxx Sometimes there's nothing left to do but crash and burn...or die trying. ======================================================================== -- 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
