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Jan/Feb 2003    by Novell Technical Services

Tips and Tricks

tip 1

Viewing the Nterprise Branch Office Boot Sequence

By default, the boot sequence is not shown when booting a Novell Nterprise Branch Office 1.0 Server console. However,it can be helpful when a Branch Office box doesn't boot properly and you need to troubleshoot. With these simple steps you can see what commands the console is performing and get to the root of your problem.

First, to view the boot process, the Branch Office console needs to be manually unlocked. This can be done by doing the following:

STEP ONE During boot up you will see, "BOOTING NOVELL® NTERPRISE™ BRANCH OFFICE™" on the server console. Wait a few seconds and go into the debugger by pressing [SHIFT] [SHIFT] [ALT] [ESC]. Be sure to wait a few seconds before entering the debugger, because if you don't, you may have to restart the server due to the keyboard being hung.
STEP TWO Entries in the debugger are case sensitive. Type the following at the debugger prompt and then press [Enter]:
c AppScreenLock=0
STEP THREE Then type .s and press [Enter].
STEP FOUR Find and document the 8-digit hexadecimal entry to the left of "Booting Novell® Nterprise™ Branch 0 (non switchable) (active)."
Depending on how far you are into the boot sequence the screen name may also be "Novell® Branch Office™ Activity scr (non switchable) (active)".
Regardless, in both cases the screen names reference Nterprise Branch Office and state that they are active.
STEP FIVE Type the following and then press [Enter]:
c <the 8-digit hexadecimal value from above>+28=0

For example:
c AppScreenLock=0 [Enter]
c xxxxxxxx+28=0 [Enter] (where "xxxxxxxx" is the 8-digit hexadecimal value from the .s command as documented in step 4 above.)

The boot sequence will become unviewable for a second time after the automatic DS repairs execute. Enter the two lines above for a second time. This time the value documented with the .s command will be to the left of, "Novell® Branch Office™ (active)." It will be a different value from the one entered the first time.

When you finish making therecommended changes in the debugger, type G and press [Enter]. After exiting from the debugger you now should be able to toggle screens using the [ALT] [ESC] keystroke sequence. To reactivate the regular Branch Office console after you are done debugging, simply reboot the server.

Note: This information should only be used as required when debugging. Changing memory addresses can cause serious server problems including permanent data corruption. If you change the wrong value by mistake, exit the debugger immediately with the .q command and restart the server. Only change memory values in the debugger under direction and supervision of Novell Technical Support.

tip 2

Speed up the Branch Office Appliance Setup by Preloading Data

During the initial setup of a Novell Nterprise Branch Office appliance, syncing the central office server with the branch office can end up being quite a time-consuming step depending on your resources. To decrease the amount of data that has to cross the wire and the time required to set up a branch office appliance, make an SMS-compliant backup of the corporate server data. Then restore the backup from tape to the branch office volume prior to installing Novell Nterprise Branch Office. After the initial data is preloaded and setup is completed on the appliance, scheduled rsync transfers will be much quicker because only the data blocks that have changed since restoring the backup to the appliance will need to cross the wire rather than the entire data set.

There may also be some instances where a branch office location is up and running for a period of time before a decision is made to rsync data to the central office location. If a substantial data set is currently in place at the branch location, do an SMS backup of the data and pre-load it to the central office volume designated for data synchronization before enabling rsync. After the initial data is preloaded, scheduled rsync transfers from the branch office will only send the changed data to the central office location across the wire.

tip 3

The DOS partition created during the image process on a Branch Office Appliance is roughly 50 megabytes. This partition is too small for coredumps.

The RSync open-source utility is based on the highly efficient rsync algorithm, which updates files on one computer so that they are identical with the files on another computer. the two computers are linked by a low-bandwidth, high-latency, bi-directional communications link.

On the Branch Office Console type the following:
Set admin debug password = <enter password here>
Set admin debug enable = yes
Then press [Enter].
These three commands automatically load dbnet6 and rdbhost.

DBNET6.NLM is required to put a coredump on a remote machine.
RDBHOST is required if you will do live debugging with RDB.EXE. Choose one of the following methods to transfer the coredump.

ONE To a server: Have IMGHOST.NLM loaded on a remote server where you plan to send the coredump.
TWO Run IMGHOST.EXE on a workstation where you plan to send the coredump. Unlock the Branch Office Console by doing the following:
login [Enter]
supervisor [Enter]
<type the supervisor password> [Enter]
unlock [Enter]
Accept the disclaimer with YES [Enter]
The console will display "Debug mode ON"
Now toggle to the console [ALT] [ESC]
or [CTRL] [ALT] [ESC] and select the system console.

Set auto restart after abend = 0 and press [Enter]. Also put this line in the autoexec.ncf file so it will continue to be active at a later time if the server is bounced.
When the server abends, select the option to take a coredump. Select "Full w/o cache".
Select "No" on compress coredump.
Select "NETWORK -- Dump Across network to remote host."
Enter either the IP address of the workstation running IMGHOST.EXE or the server running IMGHOST.NLM.

Some LAN drivers can stop communicating when DBNET6.NLM is loaded. If this happens, update to the latest LAN drivers from the hardware vendor or swap out the NIC and follow the Branch Office Documentation for LAN card changes.

tip 4

The rsync Process

The rsync open-source utility is based on the highly efficient rsync algorithm, which updates files on one computer so that they are identical with the files on another computer. The two computers are linked by a low-bandwidth, high-latency, bidirectional communications link.

To perform this feat, the algorithm computes which parts of a source file identically match parts of a destination file. The algorithm sends across the link only the parts of the source file that do not identically match parts of the destination file. The server with access to the destination file then reconstructs an identical copy of the source file.

To give you a better (but still basic) idea of how this process works, suppose you have two computers, Computer A and Computer B. Computer A has access to File 1 (the source file) and Computer B has access to File 2 (the destination file), and the two files are similar.

The file-transfer process begins when Computer B splits File 2 into a series of non-overlapping fixed-sized blocks. For each of the blocks in File 2 (the destination file), Computer B calculates two checksums (one weak, one strong) and sends these checksums to Computer A.

Computer A searches File 1 to find blocks that have the same weak and strong checksum as the blocks that Computer B sent. This is done in a single pass.

Computer A then sends Computer B a sequence of instructions for constructing a copy of File 1. Each instruction is either a reference to a block in File B or actual data. In other words, the algorithm sends over the link only the blocks from File 1 that do not match blocks in File 2 plus a small amount of data for checksums and block indexes.

Computer B uses the information from Computer A to modify File 2 to be an exact copy of File 1. The process requires only one round trip, which minimizes the impact of the link latency.

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