On Wednesday 12 March 2008 11:38:25 Michael Tokarev wrote: > Wayne Gemmell wrote: > > On Wednesday 12 March 2008 10:04:56 you wrote: > >> a) re-create the array with new partitions, with THE SAME DISK ORDER, > >> METADATA VERSION AND CHUNK SIZE as it was before. > > > > Is this possible without loosing data? > > Yes. But it's unreliable, sorta. Too easy to screw things up, that is. Thankfully I didn't need to do this. Resizing the partitions fixed that. And now for the dangerous (looking) part. > And now, the original question comes up again: what to do, how to > perform the actual resize of the raid array... > > To be fair, I don't really know. I always used my own tiny program > to assist me in a situation like this - to back up and restore > v0.90 linux raid superblocks. It's available at > http://www.corpit.ru/mjt/mdsuper.c . Here's how I use it: > > First, save the original superblocks in files: > > for f in sd{a,b,c,d,e}1; do > ./mdsuper read /dev/$f > $f > done > > this instructs mdsuper to read the superblock (v0.90 only!) and > write it to standard out. This has to be done while the array > (on original partitions) is STOPPED. > > Now, resize the partitions, reboot if necessary (for the kernel > to recognize the new sizes). You can save a dump of your current > partitions using `sfdisk -d' (redirect its output to a file as > with mdsuper) - just in case if something goes wrong. > > At this point, your array is unaccessible - mdadm will tell you > that it can't find the superblocks. But we have the superblocks > saved - so we only need to restore them back: > > for f in sd{a,b,c,d,e}1; do > ./mdsuper write /dev/$f < $f > done > > (note the redirection is opposite!, and read was changed to write!). > > Now, try to assemble the array - it should be here. We just moved > (actually copied) the superblock from the now-middle-of-partitions > to the end, where it should be, and mdadm is now able to find it. > The array is still of the old size - but now mdadm --grow will > work. > > That's basically it. Just watch the mdsuper invocation. > > /mjt > -- > 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 -- Regards Wayne Gemmell Flash Media Group Tel: 27 (0)12 430 7597 Cell: 27 (0)83 666 3342 -- 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
