Volume managment

Introduction

This document describes the definition of volumes within the Deploy exe-script command.

Motivating example

Up until now, the root file system was built using overlay-fs with the lowerdir being the .gvmi image (or rather the squashfs image contained within) and the upperdir and workdir set to a 128MiB tmpfs.

Scope

By passing a volumes field within the deployment command, the following can be achieved:

• Adding new volumes for transferring files between requestor and the VM (equivalent of VOLUME in Dockerfile).
• Having upperdir and workdir of / in either a larger tmpfs or on disk-backed storage.
• Mounting tmpfs or disk-backed storage at arbitrary paths.

Volumes

Two schemas are permitted. First, an explicit form mapping mount points (relative to root) to volume definitions (see below):

{ 
  deploy: {
    volumes: {
        "/golem/input": { host: {} }, 
        "/golem/output": { host: {} }
        "/": { ram: { size: "1g" }
    }
  }
}

As well as a simplified form if only { host: {} } volumes (equivalent to VOLUME in Dockerfile) are desired.

{ 
  deploy: {
    volumes: ["/golem/input", "/golem/output"]
  }
}

In this case, the equivalent long-form would be:

{ 
  deploy: {
    volumes: {
        "/golem/input": { host: {} }, 
        "/golem/output": { host: {} }
    }
  }
}

Variants:

host

This is used for creating a mount point for transfering files between requestor and provider. This variant is not permitted for the root directory.

ram

Name	Type	Description	Notes
size	String	size formatting below	[required]

storage

Name	Type	Description	Notes
size	String	size formatting below	[required]
preallocate	String	size formatting below	[optional] [default to 0]
errors	String	possible values continue, remount-ro, panic	[optional] [default to continue]

Size formatting

Size is formatted as a floating-point number suffixed by the unit, supporting both SI units (powers of 10) and binary units (powers of 2). The units are not case-sensitive and whitespace is permitted between the number and the unit.

Powers of 10

Long	Short	Value
b	[n/a]	10^0 = 1
kb	k	10^3 = 1000
mb	m	10^6 = 1000^2
gb	g	10^9 = 1000^3
tb	t	10^12 = 1000^4
pb	p	10^15 = 1000^5

Powers of 2

Long	Short	Value
b	[n/a]	2^0 = 1
kib	ki	2^10 = 1024
mib	mi	2^20 = 1024^2
gib	gi	2^30 = 1024^3
tib	ti	2^40 = 1024^4
pib	pi	2^50 = 1024^5

Examples

1. Root file system that can grow upto 1 gigabyte. no preallocation. container will panic if error occurs.

{ 
  deploy: {
    volumes: {
        "/": { storage: { size: "1g",  errors: "panic" }
    }
  }
}

2. Root fs, with prealoocated 10GB storage.

{ 
  deploy: {
    volumes: {
        "/": { storage: { size: "10g",  preallocate: "10g" }
    }
  }
}

3. Root fs with in memory overflow size 1g

{ 
  deploy: {
    volumes: {
        "/": { tmpfs: { size: "1g" }
    }
  }
}

4. Disable image volume definition for /golem/input

{ 
  deploy: {
    volumes: {
        "/golem/input": null
    }
  }
}