failures

A guide to how etcd, a distributed key-value store, behaves when machines, software, power, or networks fail. It covers leader and follower failures and the need for backups.

In plain words
What is it for?
Use it to plan cluster size, prepare for machine or network failures, understand member reconnection, and decide how backups support recovery.
Why use it?
It helps you understand when the cluster can keep serving requests and what interruptions or extra load to expect.

Command for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/openshift-eng/two-node-toolbox/failures
Clone the repo
git clone --depth 1 https://github.com/openshift-eng/two-node-toolbox

Made for: Claude Code.

Per session 10 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 826 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00010 $0.00826
Opus 5 $0.00005 $0.00413
Sonnet 5 $0.00002 $0.00165
Haiku 4.5 $0.00001 $0.00083

Measured yesterday against content hash 736c04841c74, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

failures scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/commands/etcd/etcd-ops-guide/failures.md · 49 lines

How it starts

The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Failures are common in a large deployment of machines. A machine fails when its hardware or software malfunctions. Multiple machines fail together when there are power failures or network issues. Multiple kinds of failures can also happen at once; it is almost impossible to enumerate all possible failure cases.

In this section, we catalog kinds of failures and discuss how etcd is designed to tolerate these failures. Most users, if not all, can map a particular failure into one kind of failure. To prepare for rare or [unrecoverable failures][unrecoverable], always [back up][backup] the etcd cluster.

Minor followers failure

When fewer than half of the followers fail, the etcd cluster can still accept requests and make progress without any major disruption. For example, two follower failures will not affect a five member etcd cluster’s operation. However, clients will lose connectivity to the failed members. Client libraries should hide these interruptions from users for read requests by automatically reconnecting to other members. Operators should expect the system load on the other members to increase due to the reconnections.

Leader failure

When a leader fails, the etcd cluster automatically elects a new leader. The election does not happen instantly once the leader fails. It takes about an election timeout to elect a new leader since the failure detection model is timeout based.

During the leader election the cluster cannot process any writes. Write requests sent during the election are queued for processing until a new leader is elected.

Writes already sent to the old leader but not yet committed may be lost. The new leader has the power to rewrite any uncommitted entries from the previous leader. From the user perspective, some write requests might time out after a new leader election. However, no committed writes are ever lost.

The new leader extends timeouts automatically for all leases. This mechanism ensures a lease will not expire before the granted TTL even if it was granted by the old leader.

Read the full file on GitHub · 49 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 49 lines · 10 tokens per session scan A 736c04841c74

Subscribe to this mod's changes

failures is a command published in the GitHub repository openshift-eng/two-node-toolbox (5 stars, last pushed 28d ago), licensed Apache-2.0. It adds 10 tokens to every session and 826 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.