A Terrible Waste

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Q J 5 4
Q 9 6 5 4
Q 10 7 3
A K 7 9 8 4
A K 9 6 3 10
A J 10 8 3 2
J 8 A K 9 5 4 2
Q J 10 6 5 3 2
8 7 2
K 7 Vul: E-W
6 Opening lead: A of hearts

WestNorthEastSouth
2 NT Pass 3 NT 4
Pass Pass Dbl Pass
Pass Redbl Allpass
North apparently got scared with a void in his partner's doubled suit and evidently redoubled S.O.S. for a takeout to another suit. A redouble with the expectation of making the contract and tweeking the opponents' nose looks too unrealistic to entertain. The vulnerability alone bespeaks a sac bid by South. And you certainly don't wanna redouble your partner's sac bids. What was the upshot?
This declarer went down only 3 tricks (while some went down 4 even in 3 spades!), which would have been minus 500 without that redouble. And the opponents. Some made 3 no, for a 600+ game, meaning minus 500 would have beat all of them for a respectable score. More went down in 3 no than made, to be sure. But South had made a decision which North can't take back, and you can only bid and play wisely from that point.
Minus 500 would have been minus 4.38 IMP's (not a good score,since so many E-W pairs were going down). But the redouble jacked that up to minus 11.71.
So I think there are two lessons here. First, though the situation may look parlous from your viewpoint, it may be that your partner has the tickets to hold the loss to a tolerable point if you'll just pass and show some trust in his acumen. And if he's wrong, then let him be wrong. You can't always adjust the bid to avoid the damages of a partner's stupidity. You've gotta live with a certain number of unfortunate bids as your partner will have to live with a certain number from you. Your task is to get your bidding right, and here that means hunkering down and seeing how well your partner fares in his bid
And secondly, the S.O.S. redouble is very questionable at high levels. There is not necessarily a better spot on every hand, as there wasn't here and you'd do well to avoid thinking you're going to solve anything with a redouble. The S.O.S. redouble works best at the one level, maybe the two, when you know you're in trouble -- say on a 3-card club suit the bidding goes one club by you, double, pass, pass -- and there is almost surely a better fit somewhere, or if not a better fit, exactly, perhaps one the opponents aren't so ready to double at the one level. At the four level, particularly when your partner has pre-empted, showing at least 7 cards, there will almost surely not be a better fit, particularly over spades, where there are no higher-ranking suits and you've gotta be two tricks better to warrant upping the level one or why bid.