---
title: "iSCSI"
description: "1 posts about iSCSI, summarised, each linking to the original."
---

# iSCSI
> 1 posts about iSCSI, summarised, each linking to the original.

## Articles

### [Making Machines Move](https://yomu.fyi/post/making-machines-move.md)
- Company: [Fly.io](https://yomu.fyi/company/fly-io.md)
- Published: Jul 30, 2024
- Type: Problem & solution

Fly.io needed to restore the ability to drain physical workers after attached NVMe volumes made stateful Fly Machines tied to particular servers. Snapshot restoration could lose data, while killing a machine before copying its volume caused unacceptable downtime; copying first risked losing writes. The solution was an asynchronous clone operation built around Linux device mapper’s dm-clone: a new volume is created immediately, reads of unhydrated blocks are fetched from the original over iSCSI, writes go to the destination, and background copying rehydrates the rest. The work also required orchestration across flyd and a fix for Fly Postgres configurations containing literal 6PN IPv6 addresses. After cautious early migrations, the infrastructure team could drain hosts without much ceremony by summer 2024, though routine automated rebalancing remained a future goal.