Put brand new RB1100AHx2 to replace a RB1000 pppoe server with 200 connections
Works a little better BUT I could not upgrade the original 5.8 to 5.12 or 5.11

creates an autosup.rif file and keeps the upgrade file like

2 name="routeros-powerpc-5.11.npk" type=".npk file" size=0
creation-time=jan/25/2012 06:39:23 contents="

10 name="autosupout.rif" type=".rif file" size=556 328
creation-time=jan/25/2012 06:44:06

Netinstall with keep configuration should work just fine.

Maybe you run out of disk space.

Connect console and then you wil lbe alb eto see what is going on in upgrade process.