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2025-07-23
Connections exhausted: look here before adding hardware
Pool sizing, slow queries holding slots, and idle-in-transaction.
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2025-07-16
What happens when Redis runs out of memory
maxmemory-policy decides between an error and silently dropping keys.
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2025-07-09
Field names in structured logs are hard to change later
Decide the conventions before the first service ships.
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2025-07-02
3-2-1 backups for a small project
Three copies, two media, one off-site — the minimum viable version.
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2025-06-25
Finding the packet dropper with the LOG target
Insert a log rule and let the kernel tell you whether traffic arrives.
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2025-06-18
A little sandboxing for systemd services
A few lines restrict what a service can write and see.
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2025-06-11
When curl -v is not enough
--trace shows every byte; --trace-time adds timestamps.
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2025-06-04
An odd one-second stall from Expect: 100-continue
The client waits for 100 while the server just answers 200.
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2025-05-28
0.0.0.0 and :: are not the same listener
Bind one family only and half the traffic cannot connect.
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2025-05-21
DNSSEC turned a working domain into SERVFAIL
A broken chain makes validating resolvers refuse, not fall back.
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2025-05-14
proxy_cache hit rate depends on the key
The default key includes the query string and the upstream host.
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2025-05-07
When variables expand inside a here-doc
One quote character decides whether they expand at all.