---
title: "Persistent Storage and Fast Remote Builds"
description: "Fly introduces persistent volumes for apps and a new remote-build path designed to make Docker image builds faster. Volumes are created through flyctl, backed by encrypted ext4 filesystems on Linux LVM2 thin pools, and attached one-to-one with app instances on compatible hosts. Volumes survive reboots and deployments and are described as performance-competitive with, usually slightly faster than, EBS, but raw-volume resilience remains the customer’s responsibility. Because volume count limits instance count and prevents an extra canary volume, volume-backed apps use rolling deployments; the post identifies replicated database clusters, caches, metrics, and restorable data as suitable cases. Remote builds now match jobs to automatically created builder apps with attached storage for cached layers and manifests; builders expose authenticated Docker servers, terminate after 10 minutes of inactivity, and are not restarted after successful exit."
---

# Persistent Storage and Fast Remote Builds

[Fly.io](https://yomu.fyi/company/fly-io) · Feb 15, 2021

**Type:** Announcement

## Summary

Fly introduces persistent volumes for apps and a new remote-build path designed to make Docker image builds faster. Volumes are created through flyctl, backed by encrypted ext4 filesystems on Linux LVM2 thin pools, and attached one-to-one with app instances on compatible hosts. Volumes survive reboots and deployments and are described as performance-competitive with, usually slightly faster than, EBS, but raw-volume resilience remains the customer’s responsibility. Because volume count limits instance count and prevents an extra canary volume, volume-backed apps use rolling deployments; the post identifies replicated database clusters, caches, metrics, and restorable data as suitable cases. Remote builds now match jobs to automatically created builder apps with attached storage for cached layers and manifests; builders expose authenticated Docker servers, terminate after 10 minutes of inactivity, and are not restarted after successful exit.

## Context

Fly’s micro-VMs were previously entirely ephemeral, making persistent storage the biggest question for developers hosting complete applications. Remote builds using AWS CodeBuild were also slow enough that the team sometimes abandoned them for local Docker builds.

## Approach / What changed

Fly added attachable volumes implemented with Linux LVM2 thin pools, encrypted block devices, ext4 filesystems, and volume-aware scheduling. It also replaced the previous remote-build path with automatically created builder apps that use attached storage to cache Docker layers and manifests and terminate after 10 minutes of inactivity.

## Takeaways

- Raw Fly volumes survive application reboots and deployments, but their resilience is the customer’s responsibility; replication must be handled at the application layer where needed.
- Attaching volumes limits an app to its number of matching volumes and changes deployments from canary releases to rolling deployments.
- Remote builder apps cache layers and manifests, authenticate flyctl to a Docker server, terminate after 10 minutes without activity, and are not billed separately.

**Tags:** [Caching](https://yomu.fyi/topic/caching), [Deployment](https://yomu.fyi/topic/deployment), [Docker](https://yomu.fyi/topic/docker)

- Source: [Fly.io](https://fly.io/blog/persistent-storage-and-fast-remote-builds)
- Source URL: https://fly.io/blog/persistent-storage-and-fast-remote-builds
- Ingested by Yomu: 2026-09-03T01:25:22.670Z

[Read original post](https://fly.io/blog/persistent-storage-and-fast-remote-builds)