Partition Management for the Debian Installer

Description

PartitionManagementfortheDebian
Installer
AntonZinovievCopyrightNotice
©2003AntonZinoviev
Thismanualisfreesoftware; youmayredistributeitand/ormodifyitunderthetermsofthe
GNU General Public License as published by the Free Software Foundation; either version 2,
or(atyouroption)anylaterversion.
Thisisdistributedinthehopethatitwillbeuseful,but without any warranty;withouteventhe
impliedwarrantyofmerchantabilityorfitnessforaparticularpurpose. SeetheGNUGeneral
PublicLicenseformoredetails.
A copy of the GNU General Public License is available as
/usr/share/common licenses/GPL in the Debian GNU/Linux distribution or on
the World Wide Web at the GNU website (http://www.gnu.org/copyleft/gpl.html).
YoucanalsoobtainitbywritingtotheFreeSoftwareFoundation,Inc.,59TemplePlace,Suite
330,Boston,MA02111 1307USAi
Contents
1 Introduction 1
2 Packageinterrelations 5
2.1 Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Menu directories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4 Setup/target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 /lib/partman/definitions.sh 13
3.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

Sujets

• CDU
• GBA
• Target Earth
• Fstab
• Document Type Definition
• Tabre

Informations

• Publié par: Astlyo
• Nombre de lectures: 115
• Langue: English

Extrait

Partition

Management Installer

Anton

Zinoviev

for

the

<[e-mail]>

Debian

Copyright Notice

© 2003 Anton Zinoviev

This manual is free software; you may redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version.

This is distributed in the hope that it will be useful, butwithout any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU General Public License for more details.

A copy of the GNU General Public License is available as /usr/share/common-licenses/GPLin the Debian GNU/Linux distribution or on the World Wide Web at the GNU website (poc/gro.ung.www/mlhtl.gpt/efyltp:/ht). You can also obtain it by writing to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

Contents

i

1 Introduction1 2 Package interrelations5 2.1 Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Menu-directories. . . . . . . . . . .  7. . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Partitioning. . . . . . . . . . .  8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Setup/target. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3/il/baptram/nedfinitions.sh13 3.1 Environment. . . . . . . . . . .  13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Menus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.3 Long numbers 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Updating partition directories 15. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 3.5 Communication withparted server 16. . . . . . . . . . . . . . . . .. . . . . . . _ 4 The commands ofparted server19 _ 4.1 Open a new device 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Close a device. . . . . . . . . . .  19. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Write partitioning to the disk 20. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 4.4 Undo the changes. . . . . . . . . . . . . . . . . . . . . . . . . . 20. . . . . . . . . . . 4.5 Dump the partitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.6 Get the partitions 20. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 4.7 Getting info about a partition. . . . . . . . . . . . . . . . . . . . .. . . . . . . . .  21 4.8 Getting cylinder/head/sector geometry of a partition/free space. . . . . . . . . 22 4.9 Getting the supported partition table types. . . . . . . . . . . . . . . . . . . . . . 22

CONTENTS

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4.10 Create a new empty partition table 22. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.11 Getting the meaningfull flags for a partition 22. . . . . . . . . . . . . . .. . . . . . . 4.12 Getting the active flags of a partition. . . . . . . . . . . . . . . . . .. . . . . . . .  23 4.13 Set the flags of a partition. . . . . . . . . . . . . . . . . . . . . . . 24. . . . . . . . . 4.14 Check if partition names are supported. . . . . . . . . . . . . . . . .. . . . . . .  24 4.15 Set the name of a partition. . . . . . . . .  25. . . . . . . . . . . . . . . . . . . . . . . 4.16 Check if extended and logical partitions are supported 25. . . . . . . . . . . . . . . _ rver temsfile sy. . 4.17 Get the known toparted ses 25. . . . . . . . . . .. . . . . . 4.18 Try to detect the file system in a partition. . . . . . . . . . . . . . . . . . . . . . . 26 4.19 Change the filesystem of a partition. . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.20 Create a file system in a partition 26. . . . . . . . . . . . . . . . . . . .. . . . . . . . 4.21 Create a new partition 27. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 4.22 Delete a partition 27. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 4.23 Resize a partition. . . . . . . . . . . . . . . . . . . . . . . . . . 27. . . . . . . . . . . 4.24 Get resize range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4.25 Copy the contents of one partition into another. . . . . . .  28. . . . . . . . . . . . .

5 Bugs and limitations

29

Chapter 1

Introduction

1

There are many wishlist features that we might desire from any installer of GNU/Linux and that are related to partitioning:

• The partitioner should support different file systems. Some of them need more care than only libraries and suitable arguments formount. • It should support not only regular partitions but also software RAID and LVM as well as encrypted file systems. • It should be able to partition disks automatically and allow the user to inspect and cus- tomise the automatical partitioning latter. • It should be able to resize partitions and move their contents from one place to another. • The users should be protected from mistakes — by allowing them to undo their parti- tioning operations. • The partitioner should discover that there is already some installed GNU/Linux system and analise itsfstab,passwd, etc. in order to provide automatic upgrade from the old already installed installed GNU/Linux system to the new one.

One nice feature of the Debian installer is that it is modular. Its components are packaged in separate udebs and they can have relatively independent development process. This document describes how we can solve all mentioned tasks keeping the Debian installer as modular as it is now. Ideally in order to add some new feature only few new udebs must be all that is needed — no changes in the existing udebs and no recompilation. The scriptpartmanfrom the packagepartmanopens the main partitioning menu; it may look like this one:

+-------------------+ [!!] Debian Installer Main Menu +-------------------+ | Please choose a partition, free space or device to edit |

Chapter 1. Introduction 2 | | | ------- IDE1 master - Seagate U Series 40810 (40.0 GB) | | #3 primary 2.1 GB B F ext3 / | | pri/log 4.4 GB FREE SPACE | | #5 logical 3.6 GB | | #7 logical 10.0 GB F ext3 /usr | | #8 logical 19.9 GB K ext2 /home | | ------- IDE2 master - Maxtor 6Y120L0 (122.9 GB) | | #7 logical 1.0 GB linux-swap | | logical 114.5 GB FREE SPACE | | #5 logical 5.5 GB reiserfs | | #6 logical 1.9 GB | | --------------------------------------------- | | Undo everything | | End the partitioning | | Commit the partitioning to the storage devices | | Abort the partitioning | | | | <Go Back> <Continue> | | | +-------------------------------------------------------------------------+ When the users choose some free space they are offered to create a new partition just like they are incfdisk users choose a partition they are offered with a menu with various. When editing operations: +-------------------+ [!!] Debian Installer Main Menu +-------------------+ | Please choose what to do with the choosed partition. | | | | Choose how this partition should be used | | Choose a filesystem | | Specify mountpoint for this partition | | Turn bootable flag on | | Resize the partition | | Copy here data from another partition | | Delete the partition | | Finished with this partition | | | | <Go Back> <Continue> | | | +-------------------------------------------------------------------------+ All udebs are allowed ot add items to this meny as well as to several other menus. They can add new items in the list of devices such as software RAID and LVM devices, net- worked file systems, encrypted partitions, etc. The packagegninoititrap-nmartpais

Chapter 1. Introduction

3

responsible for pure partitioning operationgs such as creation of new partitions and dele- tion. The packagespartman-targetandtramapdshoetcmsiban-are responsible for the items ‘Choose how this partition should be used’ and ‘Choose a file system’. The package partman-basicfilesystemsadds support forext2,linux-swap,fat16,fat32and (future version)reiserfs. The packagepartman-ext3adds support forext3.

Chapter

1.

Introduction

4

Chapter 2

Package interrelations

2.1 Basics

5

The GNU Parted disk partitioning library provides high-level, architecture independent func- tions for operations such as creating, deleting, resizing and moving of partitions as well as creating some kinds of file systems. Most of the functions of libparted work in a non nonde- structive way. The partition table is written in data structures and any change in the partition table happens only in these data structures rather than directly on the disk. This makes possi- ble to implement partitioning tools based onlibpartedthat support undoing of the editing operations. However we have to solve two problems. The first is that we want to use as much as possible shell scripts rather than C programs. The second is that different programs have to operate with same instance of libparted structures. For example the user can use some tool for auto- matic partitioning, then correct or customise the automatic partitioning, perform some other arbitrary operations being still allowed to undo everithing. There is one obvious solution of these two problems — we keep the data structures of lib- parted in a daemon process and communicate with it in order to make changes in these data structures. This process is/bin/parted serverfrom the packagepartman. _ The scripts from/d./aptril/bnitiam/nare executed before all partitioning operations. They can be used to initialise the partitioning system. The scripts may be invoked more than once in which case they should behave properly. For example this directory can contain a script to discover the existing hard drives. If invoked for second time the script must either do nothing or check if there is some new kernel module giving access to new still undiscovered device. Any udeb may install a script in this directory. For example the script/lib/partman /init.d/30partedfrom the packagepartmanis responsible to runparted server. No-_ tice that the scripts are prefixed by a two-digit number. This number determines the order the scripts are executed. If some of the scripts exits with non-zero exit code the partitioning will be aborted. This means that in almost all cases these scripts must end with exit-code 0.

Chapter 2. Package interrelations

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While the user is modifying the partitions this happens only in the memory of the computer and not in the edited devices. This is because almost all changes happen either in the data- _n the installers ram-disk. T we can provide hy structures ofparted serveror in files i hat’s w the user with the option to undo everything. When the user chooses to undo the scripts in the directorydo.d//il/baptram/nnu udeb may install a script in this di- Anyare executed. rectory. For example the script/litear0p/3damtrap/bd.odnu/nis responsible to restore _ pts fromost cases crundo.d the contents of the data structures ofparted server the. In m i s must exit with exit-code 0. If some of the scripts exits with non-zero exit code the partitioning will be aborted. In order to perform the editing operations on the storage devices (and in particular to trans- fer the partitions from the internal data-structures ofparted_serverto the hard disks) the scripts from the directorynamtmoc/bil/rap//dim.t order in which these Theare executed. scripts are executed is determined again by two-digit prefixes in the script names. Every script fromcommit.dis guaranteed that the scripts ordered before it have been already executed. However if some of the scripts exits with non-zero exit-code the execution of the scripts in commit.dwill be stopped. In this case the partitioning will continue and the user is expected to fix the problem. If some script exits with non-zero exit code it is supposed to inform the user what went wrong using debconf. There are two cases when the scripts fromcommit.dare executed. The first case is when the user wants to commit the changes to the disks but continue partitioning. The second case is when the partitioning ends. In the first case if none of the scripts fails the scripts frominit.d will be also executed and the user will be returned to the partitioning dialog. In the second case the scripts fromfinish.dIn both cases if some of the scripts inwill be executed. commit.d fails the user will be returned immediately back to the partitioning dialog. The scripts fromn/martpa.dshnifi/il/b/are responsible for final tasks such as to mount partitions on/target, generate offstab, stopparted_serveretc. 1 If some of these scripts exits with non-zero exit-code the execution of the scripts will be stopped. If the exit-code was 1 then the user will be returned back to the partitioning dialog and is expected to correct the problem. If the exit-code was neither 0 nor 1 then the partitioning will be aborted. For every hard disk in the system the scriptrap03/d.detlib/partman/init/creates a subdirectory invicen/des//ril/avtram/bapand informsparted_serverthat the de- vice is to be edited (‘opens’ the device). All udebs that provide storage device (software RAID, LVM, encrypted partitions) must do the same. This subdirectory must contain at least three files —device,modelandsize. The first contains the name of a device file (for exam- plec/dis0nul/0tegrat/0su/bt0os/hde/iev/d second contains the name of the). The device (for example ‘Maxtor 6Y120L0’). The third contains the phisical size of the storage device (in bytes, for example ‘122942324736’). 2 The subdirectories of/var/lib/partman 1 What tasks will be performed depends on what udebs are unpacked. If the packages respon- sible to mount partitions and create fstab are not unpacked we have only a simple partitioner pro- vidingpartitioned-harddrives they are unpacked they provide also. Ifmade-filesystemsand mounted-partitions. 2 storage ‘devices’ that can not be partitioned (such as net-Please notice that udebs that provide support for worked file systems) should not create a subdirectory in/var/lib/partman/devicesand certainly can not provide the device to the management ofparted_server.

Chapter 2. Package interrelations

7

/devices/ We call these subdi-can but are not obligated to contain additional information. rectoriesdevice directories. Every partition in a device managed byparted_serveris given an unique name hav- ing the formfirst_byte-la _ yte name can be used to determine where the parti-. This st b tion starts and where it ends. 3 If the device directory contains a subdirectory named _ _pehtitraanyoritsueorboirbdtoecotnhteinesu.iWs first byte-last byteth st informat call this subdirectorydirectory of the partition call the string. Wefirst_byte-last_byte‘id’ of the partition.

2.2 Menu-directories

There are several menus involved in partitioning. In order to keep the Debian installer modular and extensible we want to allow every udeb to install items in these menus. Let we be more specific. When the users decide to format some existing partition we need a menu with an item for every supported file system. Obviously we don’t want to hardwire the list of the supported file systems in any place of our installer. If we want to add support to the installer say for XFS or UMSDOS file systems, only few new udebs must be all that is needed. In order to achieve this flexibility the packagepartmanprovides support for the so caled menu-directories. Every such a directory contains files namedquestionandpriority. They contain the name of a Debconf template and the priority of the question correspondingly. The template must have exactly the following type and choices fields:

Type: select Choices: ${CHOICES}

All other files in the menu directory are subdirectories. Any udeb can install such a subdirec- tory in order to add items to the menu. For example the udebs for software RAID volumes can install in the menu of the editing operations an item to resize the choosed partition to have the same size as another. These subdirectories must contain two scripts —choices anddo_optionof the first script is to print menu items. purpose . The every menu item For choicesmust print a line having the form

_ _ menu item id<TAB>The text for the user

The scriptchoices Inis allowed to print nothing. this case no item for the menu is created. Here<TAB> The text ‘The text for the user’ will be presented to the users. If theyis ASCII 9. choose this particular menu item the scriptdo optionwill be invoked. _ The scriptchoicesarguments depending on the particular menu-may be given some directory. The first argument given todo_optionis always themenu item idof the _ _ 3 Unlike one can supposeparted_serverand places in bytes rather than in sectors.always measures sizes Last_bytebyte of the last sector of the partition.is the number of the last