>>>>> "Jamie" == Jamie Lokier <jamie@xxxxxxxxxxxxx> writes: Jamie> Does it handle devices with different properties in differeng Jamie> offset ranges? E.g. a RAID setup where the first 100GB have Jamie> one stripe width, but the next 100GB have a different stripe Jamie> width - as you can get if you join two different hardware RAIDs Jamie> with LVM, for example. I touched on this in my reply to Andreas. The values exported in sysfs are only part of the solution. We'll still need some intelligence (in libdisk or elsewhere) to traverse the stacked device. And that's better done in user land where it's easier to notify the operator or ask for confirmation. Jamie> If it's a set of drives, doesn't it need to return multiple Jamie> offsets, and drive identities? Given the almost infinite amount of stacking and concatenation options I think we'll quickly get into FIEMAP territory. Add snapshots to the mix and mapping out the characteristics quickly becomes unmanageable. If we present the mkfs writers with a list of 200 regions with different alignment criteria and stripe sizes I'm sure they'll get very unhappy. So instead of publishing all this information I'd much rather have libdisk do a rudimentary check and make it a binary "looks good" vs. "may have performance problems". If some poor mkfs souls wantsto traverse the entire stack and actually make the filesystem layout completely heterogeneous, my patch also allows them to do that... -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
