On 7/2/2010 10:11 AM, Czarnowska, Anna wrote:
2. Policy definition Array auto rebuild configuration is based on DOMAIN lines in /etc/mdadm.conf config file. Only this standard config file is supported. The DOMAIN line defines a set of devices determined by path and platform. Mdadm will take the same actions for all devices in the same domain and subset. Subsets are parts of domain specific for hardware controllers and metadata spare groups (such as storage pool id to be implemented at a later stage). An array cannot include members and spares from more than one domain and subset. Spare migration happens only within a subset. It is possible to ignore subsets by using -force option. Domains are matched from top down i.e. first line from config file that matches given device is taken. Therefore the order of domains in config file is important. With no DOMAIN lines in config file four default domains are assumed, one for each metadata type: 0.90, 1.x, ddf, imsm.
It seems this implementation was not re-evaluated in light of Neil's policy framework announcement [1] sent a couple days ago. I think there are some significant differences, especially with regard to how domain definitions stack, and how metadata handlers can tag devices and arrays with domain information. Having a default domain per-metadata type does not gain us anything because devices with metadata are already associated by way of having the same metadata.
Please review the proposal on the table as I think it makes a lot of things easier. Especially the requirement for tagging arrays with domain information. It eliminates the ambiguity of determining an array's domain so we don't need to guess when an array appears to straddle two domains.
-- Dan [1]: http://marc.info/?t=127796713700001&r=1&w=2 -- 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
