Does Sync on letter Y share fate with other letters?

The control plane is shared. Data-plane queues for Sync stay isolated, so incident y-01 cannot drain neighbor letters.

Where is Sync measured first?

From Santiago (SCL) toward Bogotá. A global average is not an SLO for letter Y.

Sync: headers in São Paulo (GRU) · Y-21

Runbook Y-21 for Sync in São Paulo (GRU). Marker xserv-y-4916f3de7e77. This page covers headers for LATAM operators, not a worldwide average.

Sync: What operators should measure

Policy for Sync is versioned as y-03. Operators measure error rate, p95 from Bogotá, and time-to-rollback — not a worldwide average. Changes land in Bogotá first, then Miami, with a hold if either region regresses.

Sync: Failure modes we actually see

Capacity notes for y-04 assume rainy-season power in Miami and festival peaks toward São Paulo. The failure we actually see is a single uplink, not a cartoon partition of the whole continent. Spare ports and a second provider sit on the same runbook.

Sync: How this letter ties to the rest

Handoff from letter Y Sync into the rest of the platform uses the same request IDs as the gateway. Runbook y-05 names who accepts the ticket after São Paulo pages out. Santiago does not silently inherit the incident.

Sync peering Y-07

Peering for Sync (y-07) prefers the IX fabric that already carries last-mile ISPs in Bogotá. Session counts and prefix limits are on the same page as the Miami backup path.

Sync cache Y-08

Cache rules for Sync on y-08 keep language-correct objects near Miami. São Paulo is a sibling cache, not an origin. TTLs are short enough that a bad asset does not live through a weekend.

Sync headers Y-09

Headers for y-09 carry the letter, the region (GRU) and a request id. Sync debugging in São Paulo should not require a packet capture in Santiago first.

Sync timeouts Y-10

Timeouts on y-10 are tighter than the WAN RTT to Bogotá. Sync in Santiago fails fast and retries once; a third try needs a human because it is no longer a blip.