begin documenting migration from megaraid to md

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+In our testing, md raid10 is about 30% faster than megaraid's internal raid10.
+
+Here are steps to replace hardware megaraid with software md5 on ganeti.
+
+
+
+
+root@lib30:/srv/gnt-info# gnt-node migrate lib28
+
+root@lib30:/srv/gnt-info# gnt-node modify --drained yes lib28
+
+root@lib30:/srv/gnt-info# hbal -L -X
+
+
+
+This will migrate instances from node, marked it as drained and then hbal will re-distribute drbd disks
+from it to rest of cluster.
+
+Alternative is to use modify -t plain, but that requires instance reboot.
+
+