These boxes are well out of warranty so they need to go away. Steps required for this to happen:
[x] snapshot jobs moved off these hosts
[x] mounts removed from snapshot hosts
[x] web service moved to labstore1006,7 (T188641, T188646)
[x] nfs mounts to stat1005,6 moved to labstore1006,7 (T188644)
[x] incoming fetches of datasets moved to labstore1006,7
[x] incoming pushes of datasets from other hosts moved to labstore1006,7 (T171541)
[x] ezachte's cron jobs updated to use labstore1006,7 instead of dataset1001
[x] get all mirror sites to switch over to labstore1006,7 (T188645)
[x] service of dumps and pageviews via labstore1006,7 instead of labstore1003 (T188643)
[x] turn off all cron jobs involving dataset1001, ms1001
[x] remove all mention of dataset1001, ms1001 from rsync config files
[x] change roles on dataset1001, ms1001 to spare system
[] Profit??
This may not be quite the complete list but it should be most items. Some of these items are also listed on this task: T168486
I have them here for my own bookkeeping.