Articles

Notes from the job

Longer write-ups of things that come up in this work: how big an AI server needs to be, backups that won't restore, certificates that expire every month, order mail in the spam folder.

Private AI How big does a local AI server need to be? How much GPU memory a private language model needs, why the number of people using it matters less than you'd think, and how big the document index gets. A way of working it out, instead of a shopping list. 9 min read

Managed servers What we let AI agents do on a server, and what we don't Agents are good at watching servers, linking up symptoms and writing the fix. The hard part is deciding what they may do without asking. The four groups we use, and the safeguards around them. 8 min read

High availability & cloud What 99.9% actually means, and what more nines cost An availability target turns into minutes of downtime, gets worse with every dependency, and can be undone by one failure that hits every redundant copy at once. How to pick a target your setup can really meet. 7 min read

Security & continuity Your backup job says OK. That doesn't mean you can restore A backup job that finishes without errors tells you something was copied. Whether you can get a working system back, and how long it takes, you only find out by restoring it. Here's how we do that, and what we write down each time. 8 min read

E-commerce platforms Getting a PrestaShop or Magento shop through Black Friday Peak traffic rarely breaks a shop in a new way. It finds the slow query, the uncached page and the flaky payment callback that were already there. What we check, in what order, and when to stop changing things. 9 min read

Managed servers Nagios alerts that only wake people up when they have to If an alert doesn't need anyone to do anything, it's noise, and noise teaches people to ignore alerts. How we split alerts into the ones that page someone and the ones that wait for the report, with the Nagios settings to do it. 8 min read

Managed servers Certificates now last 200 days, and soon 47 Since 15 March 2026 a public TLS certificate can't be valid for more than 200 days, and by 2029 the limit is 47. Renewing by hand stops working. What to list, what to automate and how to notice when the automation quietly fails. 7 min read

E-commerce platforms Why your order confirmations end up in spam When order mail lands in the spam folder, it's nearly always a setup problem. How SPF, DKIM and DMARC work together, what "alignment" means, and how to get from p=none to p=reject without losing mail on the way. 9 min read

Managed servers Locking down SSH on a server that faces the internet regreSSHion and Terrapin were reminders that SSH needs looking after like anything else. The baseline we put on every server: patches first, keys only, no root login, a short list of who may log in, and an audit we can repeat. 7 min read

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