QEMU – A Crucial Building Block in Digital Preservation ...adt.cs.upb.de/quf/quf11/quf2011_08.pdf- to document and preserve of user interactions and interactive processes in ancient

QEMU – A Crucial Building Block in Digital Preservation Strategies Klaus Rechert, Dirk von Suchodoletz, Achille N. Tchayep University of Freiburg, Germany

Digital Objects: A Risk Analysis

§  Physical Risks -  Due decay of media (especially unprotected media like

CDs/DVDs) -  Deprecation of connectors and standards

§  Technological Risks -  Even with succesful bit-preservation rapid changes in

technological environment •  Changes in (G)UI concepts, hardware architectures and

OS -  E.g. IBM-8088 PC/XT à iPad

•  Old (proprietary) file formats -  E.g. WordStar, Lotus AmiPro, AutoCAD ...

§  Intellectual Risks -  Changes in contextual knowlegde

•  Missing / incomplete documentation •  Lost context for single dig. objects.

18.03.11 1st International QEMU Users Forum (QUF’11) 2

From Risks to Solutions

§  Research Domain of Digital Preservation pretty young but differentiates into sub domains

§  Our specialization is preservation action: à Emulation


Dynamic Digital Objects

§  Objects like -  Applications -  Operating systems -  Databases

§  Non-linear, user inter-action, multiple views

§  Not many options: -  Print source code,

adaption to recent environments

-  Video-recording, screenshots of game or application session

-  Emulation


Emulation as Digital Preservation Strategy

§  No changes on object, but reproduction of original environment -  Emulators around for quite a while, supplemented

by virtualization -  Can operate on different layers of software/

hardware stack -  Number of objects to cover differs significantly;

thus hardware layer seems very attractive to focus on


Emulation as Digital Preservation Strategy

§  More complex approach involving larger number of additional software components, complexities: -  Standalone emulation is not sufficient -  Different sectors of ongoing research -  Several open issues


Access to Emulation

§  DP emulation services should allow -  to view digital objects and

compare digital objects in their original environment,

-  to experience ancient (graphical) interactive user environments,

-  to document and preserve of user interactions and interactive processes in ancient user environments,

-  to migrate files using the original application in emulation in an automated way.


QEMU as a Digital Preservation Tool

§  QEMU is „digital preservation aware“ through abstract interaction interfaces: -  VNC

•  Remote emulation services •  Automation of interactions (replay)

-  Migration-by-emulation -  Automated testing

-  monitor-Interface •  Offers controls like power/reset-button •  Load / eject removable media (floppy/CD-ROM)


QEMU as a Digital Preservation Tool

§  Open Challenges: -  For large scale preservation tasks, preservation

planning tools like PLATO are used for cost estimations.

à Use QEMU to measure and predict costs of large scale DP-preservation tasks

•  Predict CPU-time/wall-clock time (on host system) •  Memory consumption etc...

-  Usability of QEMU monitor interface needs improvements:

•  Operate complete guest session by sending sequences of keystrokes and mouse events.


Preserving Emulated Hardware

§  Digital preservation depends on stable virtual machine hardware -  Bridges the widening gap between digital past and

todays current environments. •  E.g. DRDOS, Windows 3.x/95/NT, OS/2 are not

maintained anymore à no support for new (virtual)hardware, especially network and video.

à Reproduction of old software environments depends on emulators like QEMU providing necessary hardware configuration. E.g.:

•  x386 ISA bus machine •  NE2000 network adapter •  Soundblaster 16 •  Simple VGA


Preserving Emulated Hardware

§  QEMU has a pretty good history of maintaining once introduced hw-components.

§  However: -  Support for older Windows versions was rocky

•  For some floppy support did not work •  Some versions could not start Windows 9X at all •  Mouse support affected by migration from Bochs to

SeaBIOS -  Other major issues

•  Currently Cirrus Logic VGA is unusable in Windows 3.11

•  PIIX3 IDE not recognized by Windows 95 and official drivers


(Automated) Regression Testing

§  Software testing in general is a difficult task. §  As we are interested in preserving support

for old systems we propose a pragmatic approach: -  Black-box testing:

•  Booting from different media •  Checking screen resolution, network, keyboard

and mouse functionality •  Booting various (old) OS. Check if they operable

for defined tasks •  Start applications and execute actions


(Automated) Regression Testing


Test Example

§  Test Case -  Boot Windows 3.11 image from harddisk -  Install Lotus Ami-Pro from CD -  Test case was recorded on qemu-10.6

§  Tested Emulators -  qemu-11.1, qemu-12.4, qemu-12.5, qemu-13.0,

qemu-14.0 §  Result

-  Test failed with qemu-12.4, qemu-12.5 -  Reason: no mouse control through VNC


Challenges and Chances

§  QEMU faces same problems like other digital objects: feature development and updates -  without changing the API to original host environments -  “stable” virtual hardware

§  Integration into digital preservation frameworks: -  to automate procedures to be run on thousands of

objects §  Definition of a proper feature set for

preservation-aware emulators -  E.g. expose internal behavior

§  (Automated) Regression testing for old systems -  Leveraging the growing emulation user community in

digital preservation (e.g. comprehensive software archive)


Thank you for your Attention!

Questions / Comments?


Klaus Rechert Chair in Communication Systems Faculty of Engineering University of Freiburg / Germany [email protected]

Documents

QEMU – A Crucial Building Block in Digital Preservation ...adt.cs.upb.de/quf/quf11/quf2011_08.pdf- to document and preserve of user interactions and interactive processes in ancient