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XX-8266A-25

2010

25 pages

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Document:	Risk vs Benefits of VAX-Alpha Emulation
Order Number:	XX-8266A-25
Revision:	0
Pages:	25
Original Filename:	Risk%20vs%20Benefits%20of%20VAX-Alpha%20Emulation.pdf

OCR Text

Risks vs. Benefits of VAX/Alpha Emulation
Stanley F. Quayle, P.E.
18 Years of VMS Consulting

Today’s Goals
• Recognizing candidates for emulation
• Preparing for emulation
• Minimizing migration time
• Validating the migration
• How to discuss the value of a solution, not just the cost
• Available emulators

Shameless Plug Alert ™
• Quayle Consulting Inc. is a Value‐Added Reseller (VAR)
of the CHARON‐VAX and CHARON‐AXP products
manufactured by Stromasys.

Everybody’s Doing It
• Virtual Systems are everywhere!
– VMware, Xen, etc. for Intel
– AS/400 emulators
– Data General emulators
– OpenVMS under HP‐UX

What are the Benefits?
•
•
•
•
•

Improve up‐time and reliability
Save floor space, power, maintenance costs
Make the application faster
Make the system “fit” into the current data center design
Preserve the past investment in the application

The hope is that an emulator will allow the use of new
hardware in the future, without having to change the
application

When Not to Emulate – Part 1
• Dependent on instruction timing
– Example: MicroVAX II controlling linear accelerator

• “Magic” hardware
– Example: Space Shuttle ground test equipment
– Q‐bus is supported by some emulators
– Other DEC buses are not supported by anything

• Some equipment doesn’t have modern interfaces
– 8” floppies
– DSSI disks, CI, video disks
– DECtalk

When Not to Emulate – Part 2
• Applications that provide life support
• No way to “image” existing system to emulator
– Do you have the original media?
– Is it readable?
– And how do you get the data over?

• Is it acceptable to validation authorities?

When Not to Emulate – Part 3
• Impossible validation requirements
– Can you really test 232 cases?
– Got any missiles handy?

• Impossible contracting requirements
– Is it wise to replace a system that comes with a 12” thick
contract?

Good Candidates for Emulation
The emulator maps modern hardware into something
that the old application and OS recognizes:
• Network connections
• Serial ports
– Terminal servers are “network” devices

• Disks
• Tape drives

What are the Risks?
• The emulator may not replicate the original system
faithfully
• The emulator may fail, dropping users or even corrupting
data
• The host system could fail, making the virtual environment
inaccessible
• Non‐VMS system administrators don’t understand the
solution
• Some customers try to go “cheap”
– Run under VMware
– Non‐server hardware

Risk vs. Benefits
• The emulation provider and the customer must work
together to decide whether emulation is the best solution
• How about VEST/AEST instead?
– Middleware dependencies
– Licensing dependencies

• Do you have current OS and application experience?
• I tell customers:
“If you like your application before emulation, you’ll like it more
after. If you hate your application before emulation, you’ll hate it
just as much.”

Preparing for Emulation – Part 1
• Evaluate all software licenses for validity on emulated
system
– HP, Oracle, Process Software transfer licenses
– Other 3rd‐party licenses, especially Ross Systems licenses

• Develop a validation plan
– Customer’s disaster‐recovery plan can be a good starting
point
– Heavy customer involvement – to “buy” the migration,
they need to “buy” the validation

• A proof‐of‐concept migration might be necessary

Preparing for Emulation – Part 2
• Do everything on the original system that you can
– Load migration scripts
– Test disks for integrity (ANALYZE/DISK for VMS)

• Get temporary addresses (IP, DECnet, etc.) to use on
emulator while copying the OS and application
• Install emulator and build empty disk files
• Quiesce the system
– Shut down databases
– Lock out users
– Stop queues

Minimizing Migration Time
• The data copied fastest is the data that isn’t copied
– Delete/purge log files and other cruft
– Compress stuff that won’t be needed immediately
• ZIP and similar tools are widely available

• Find stuff that can be copied before the migration
• For a network copy, make sure you get max bandwidth
• Parallel streams help
– Example: Three source VAX systems each with a tape drive,
copying to 3 tape drives on the emulator

Validating the Migration – Part 1
• Attempt to mount the disks
• Validate the disk structures
• Boot from the system disk image, bypassing any
application startup
– Analyze & fix any startup errors, or prove that they’re
identical to those on the original system

• Verify access to disk drives, tape drives, serial ports,
network, etc.

Validating the Migration – Part 2
• Make changes as necessary
– In VMS, create logical names to map old device names to
new names, etc.

• Have client execute validation plan
– You might have to help the customer, or even do the
validation yourself
• Quote this up‐front on a T&M basis, so there are no surprises

Value vs. Cost
• You must be able to demonstrate that the solution will
provide more value (reliability, etc.) than it costs
– No one buys a computer to just take up floor space – they
need to run an application
– If price was the only consideration, we wouldn’t have cars

• Technical people are generally not trained in sales
• Emulation should be just one of many tools you have

Emulator Choices – SIMH
SIMH is an open‐source VAX and PDP‐11 emulator
• The price is right: free
• Some support is available
• If it breaks, you own all the pieces
• No direct access to hardware
• Not certified by HP as being a true emulation of a VAX

Emulator Choices – CHARON‐VAX
CHARON‐VAX is a commercial‐grade VAX emulator
• Certified by HP as being a true emulation of a VAX
• Support is available through VARs and Stromasys
• Products range from 128 MB single‐processor systems to 3
GB, 6‐processor SMP systems
• Can access physical disk and tape drives, including SAN
storage
• Some support for some other devices in CHARON‐TB
version
• Thousands of systems installed world‐wide
• Hosted on Windows or Integrity OpenVMS

Emulator Choices – NuVAX
NuVAX is a commercial‐grade VAX emulator
• Certified by HP as being a true emulation of a VAX
• Support is available through VARs and The Logical
Company
• Comes with dedicated server and optional Q‐bus card
cage
• Real‐time host OS (QNX)
• Replicates most original VAX instruction times

Free Alpha Emulators
These emulators are a way to “give back” to the VMS
community. They also provide a pool of volunteer beta
testers. They offer limited memory, disks, and performance.
• PersonalAlpha (Stromasys)
– Limited version of CHARON‐AXP
– Not for commercial use

• FreeAXP (Migration Specialities)
– Can be used for low‐performance commercial applications

Both run on 32‐bit Windows

Emulator Choices – CHARON‐AXP
CHARON‐AXP is a commercial‐grade Alpha emulator
• Passes all Alpha architecture validation tests
• Support is available through VARs and Stromasys
• Products range from AlphaStation 200 to 32‐processor
AlphaServer GS320
• Can access physical disk and tape drives
• Installed base in the low hundreds
• Requires 64‐bit Windows host

Emulator Choices – Avanti
Avanti is a commercial‐grade Alpha emulator
• Support is available through VARs and Migration
Specialities
• Will be available soon
• Host OS can be 64‐bit Windows, Linux, or Integrity

Emulator Choices – PDP‐11
• Some emulators:
– SIMH
– NuPDP from The Logical Company
– CHARON‐TB from Stromasys
– Osprey from Strobe Data
– Ersatz‐11 from D Bit

Questions?