The document discusses replacing aging VAX systems with VAX emulation. It covers choosing an emulator like CHARON-VAX, evaluating current systems to determine emulation needs, choosing a host platform like Linux or Windows, sizing the host system for performance, migrating disks and backups, creating a migration plan, and post-migration support considerations. The goal is to cost-effectively extend the life of applications and data using VAX emulation rather than costly system upgrades or porting.

1. Replacing VAXen
with VAX
Emulation
Stanley F. Quayle, P.E.
President
Quayle Consulting Inc.

2. Session goals
 Whether VAX emulation makes sense
 How to choose the best emulator and platform
 How to get started
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 2

3. What about porting?
 Do you have the design documentation?
 Do you have all the source code?
– What about DECmigrate (OMSVA)?
– VAX SCAN, Dibol, LISP, OPS5, RPG
 Operating system dependency?
 Hardware dependency?
 Target platform
– Can code really be reused?
– What about stability?
 Can you validate the result?
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 3

4. Wine, FreeVMS, and ACCELR8
Application Application
Layered software
System libraries
System library
Operating System interface routines
CHARN-VAX
Host OS
Real
Host OS
Host CPU(s)
Hardware
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 4

5. How hardware emulation
works
Application Application
Layered software Layered software
System libraries System libraries
Operating System Operating System
Emulator
CHARN-VAX
Real
Host OS
Host OS
Hardware
Host CPU(s)
CPU(s)
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 5

6. The emulator task
Memory disk
Ethernet
CPU Disk controller
virtual disk
Emulation
Tape controller
Clock Serial ports virtual disk
tape image
System Serial External SCSI
Console Devices Tape & Disk
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 6

7. CPU emulation
“TSTL XYZ”
 Retrieve state information from internal registers
 Fetch the instruction from memory
 Decode the operation to be performed
 Retrieve inputs from memory as needed
 Perform the operation
 Write results to memory as needed
 Update internal registers with the new state
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 7

8. The emulator task
Memory disk
Ethernet
CPU Disk controller
virtual disk
Emulation
Tape controller
Clock Serial ports virtual disk
tape image
System Serial External SCSI
Console Devices Tape & Disk
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 8

9. Cost versus benefit
 The high cost of downtime
– Customer impact
– “Above the Fold” on Wall Street Journal
– Data Loss
 Saving money on maintenance
– It’s cheap to replace a PC
– Limited support vendor choices
– Hardware support for some VAXen is unavailable
 Improved performance
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 9

10. Available emulators
 Open-Source
– SIMH
– TS-10
– Others
 Freeware
– PicoVAX
 Commercial Product
– CHARON-VAX
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 10

11. Open source or commercial?
 Open Source
– Free: Can be downloaded from the Internet, including
source code
– User-extensible
 CHARON-VAX
– Certified by HP as being a true emulation of a VAX
– Supports Q-bus hardware
– Dynamic Instruction Translation
– Training, installation, configuration, migration, and support
are available
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 11

12. Evaluating the current
system
Major Items to Check
 CPU usage, memory size, number of users/processes
 Network
– Protocols: DECnet, IP, LAT, cluster, IEEE 802
– DECwindows
– Connections
 Disk drives: size, type, shadowing
 Tape drives
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 12

13. Evaluating the current
system
Major Items to Check
 VMS version
 Layered product versions
 Application
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 13

14. Evaluating the current
system
Risky areas
 Serial lines
– Terminal servers
– VAX serial lines
• Console
• Modem
– H3104, DHV-11, etc
 Licenses
– Network MAC address as “key”
– CPU characteristics as “key”
– VMS license requirements vs. emulated system
– “It works” vs. “Is it legal”
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 14

15. Evaluating the current
system
There Be Dragons Here
 Operating systems
– NetBSD
– Digital Unix
– AT&T System V
– VAXELN
 Special hardware
– Bus: CI, M-bus, SBI, Turbochannel, UNIBUS, VAXBI,
XMI
– Disk interface: MASSBUS, SDI, ST-506 (MFM)
– Some hope for: DSSI, Q-bus
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 15

16. Special hardware: Q-bus
PCI bus Cable Q-bus rack
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 16

17. Choosing the host platform
 Alpha OpenVMS
– Unquestionable stability
 Linux
– Inexpensive
 Windows
– Inexpensive
– Q-bus support
– “Industry standard”
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 17

18. Sizing the host platform
“You can’t have too much”
 Server-class
– As fast as possible
 Memory
– More with DIT
 Processor
– Dual processors
 Disk
– SCSI
 Network
– Separate network adapter
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 18

19. Performance
50 MicroVAX II
45 VAX 11/780
40 VAX 3100 model 80
35 VAX 4000, model 500A
30 VAX 4000, model 700A
25
VAX 7000, model 710
20
CHARON-VAX/XM on dual AMD 1.6 GHz
15
CHARON-VAX/Industrial on 2GHz Intel
10
5 CHARON-VAX/AXP on 1 GHz Alpha EV68
0 CHARON-VAX/XM Plus on 1.4 GHz dual CPU Intel
CPU model - VUPs (VAX Unit
CHARON-VAX/XM Plus on dual AMD MP2100+
of Performance)
Sources: HP and Software Resources International S.A.
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 19

20. Disk migration
 Direct disk access
– SCSI? Just plug it in!
 Cluster
 Network
– COPY or COPY/FTP
– BACKUP
– MKIMAGE
– Poor Man disk driver
 Tape
 Serial
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 20

21. Backup strategies
 Tape
 Network
– TCP/IP to host
– NFS
 Host
– Disk images offline
– Disk images online
– SCSI disks
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 21

22. Write a plan
 Disk migration
 Backup scheme
 Necessary updates
 Test
– Connectivity
– Application
– Limited user access
 Going live
 Backout plan
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 22

23. Post-migration
And they lived happily ever after…
 Hardware support
 Software support
 System administration support
 New versions
07/09/09 HP World 2003 Solutions and Technology Conference & Expo page 23

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