celld v0.3.0's replicated write-behind log cuts S3 costs from $600k to $4k/month

andersonbcdefg · x · 2026-08-21

Developer roughsea released celld v0.3.0, introducing a replicated write-behind log — hopefully the last major architecture change. The goal is scaling to a Discord-sized site where every channel is a cell, an estimated 4B messages/day.

Previously celld wrote to S3 per message (46k PUTs/sec, $600k/month in write ops alone). The new version buffers before sending to object storage, cutting it to 300 PUTs/sec ($4k/month). Durability isn't weakened: writes aren't ack'd until persisted on three disks, and crashes during the buffer window can recover from peers, achieving RPO=0 and surviving the loss of an availability zone.

Original post →

More from Infra

• Moore's Law Fading: Non-Silicon Computing and Novel Architectures to See Capital Influx — MikePFrank · 2026-08-21
• "Why do we need more datacenters? Just write faster kernels" — basedjensen · 2026-08-21
• Cornell Nested Architecture Cuts Training Compute by 36% — burkov · 2026-08-21
• Tencent releases FlashPrefill V2 for efficient long-context LLM serving — tencent · 2026-08-21
• SGLang author asks community for pain points, vows to fix them — BanghuaZ · 2026-08-21
• Local LLM upgrade dilemma: Dual NVIDIA or switch to AMD? — thatObstinateGuy · 2026-08-21

Infra channel →