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From: Dominik Csapak <d.csapak@proxmox.com>
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Date: Fri, 7 Mar 2025 10:33:48 +0100
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Subject: [pbs-devel] [PATCH proxmox-backup] docs: fix hash collision
probability comparison
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Commit:
efc09f63c (docs: tech overview: avoid 'we' and other small style fixes/additions)
introduced the comparison with 13 lottery games, but sadly without any
mention how to arrive at that number.
When calculating I did arrive at 8-9 games (8 is more probable, 9 is
less probable), so rewrite to 'chance is lower than 8 lottery games' and
give the calculation directly inline as a reference.
Suggested-by: Dietmar Maurer <dietmar@proxmox.com>
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
@Thomas: if you can remember how we arrived at the '13' all those years
ago, we could check if that calculation makes more sense than what I'm
doing here, and rererence it?
docs/technical-overview.rst | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/docs/technical-overview.rst b/docs/technical-overview.rst
index 6a76942f1..fdeb3a093 100644
--- a/docs/technical-overview.rst
+++ b/docs/technical-overview.rst
@@ -298,8 +298,8 @@ will see that the probability of a collision in that scenario is:
For context, in a lottery game of guessing 6 numbers out of 45, the chance to
correctly guess all 6 numbers is only :math:`1.2277 * 10^{-7}`. This means the
-chance of a collision is about the same as winning 13 such lottery games *in a
-row*.
+chance of a collision is lower than winning 8 such lottery games *in a row*:
+:math:`(1.2277 * 10^{-7})^{8} = 5.1623 * 10^{-56}`.
In conclusion, it is extremely unlikely that such a collision would occur by
accident in a normal datastore.
--
2.39.5
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