RD Controls Software Release No. 44.1<P> <b> PCBACKUPS</b>

RD Controls Software Release No. 44.1


D.S. Baddorf

Changes in this document version:

What and Why:

The AUTOBACKUP scheme is designed to do semi-automatic backups of IBM PC type computers to the WARNER cluster disk system. As part of the nightly unattended VAX backup procedure, the PC disk images will be saved to helical scan tape cartridge. The user's PC must be configured with an Ethernet interface and connection to the Ethernet cable, and must be licensed to run DECNET-DOS.

The scheme employed relies on the MS-DOS XCOPY utility. DECNET-DOS is used to transparently provide a virtual disk, which is physically located on the WARNER VAX cluster, for use by the XCOPY utility. At this time full-disk backups of MS-DOS drives are always made. This allows for full or selective restore without the need to guess ahead.

This automated backup service is supplied only to those nodes belonging to the RD/EED Controls Group and a few special nodes belonging to the RFD department. Nodes must be registered with Deb Baddorf and some setup must be done in order to participate in the AUTOBACKUP.

Required User Actions:

PC owners are expected to insert the AUTOBACKUP floppy diskette (or specialized diskette version AUTOBACK36) in drive A: and boot the computer when leaving for the day. The keyboard can be locked up. In the morning, the user should remove the AUTOBACKUP diskette and reboot from the hard disk drive before using the PC for the day.

What Goes On:

The AUTOBACKUP diskette will boot a minimal system, installing only the hard disk driver, the ANSI terminal driver and DECNET. The AUTOEXEC.BAT file will start a tiny batch file, C:\DECNET\AUTOBACK\DOIT.BAT, which has been created on each node capable of participating in this scheme. This in turn copies file PCBACKUP.BAT to the hard disk and then starts it up with the necessary parameters for the particular PC node in question.

The node will begin a loop in which it looks for a special file on the WARNER cluster, waits 5 minutes, and then looks again. Each node looks for a file with its own name in the PC$BACKUPS directory (for example: PC$BACKUPS:EEDWRK.GO for Walter Knopf's node). At 4 p.m. each weekday night a program on the VAX will create a bunch of nodename.GO files to indicate which nodes will do backups, and nodename.NO files to indicate which nodes will NOT do backups that night. Nodes which find their GO file will begin doing backups. Nodes which don't find a GO file with their name will look for a nodename.NO file to signal that it is NOT their turn. If they find neither a GO nor a NO file, they will continue to loop looking for them until such time as the VAX job creates one or the other. This is normal. Due to disk space considerations, we are currently going to do each PC once a week. However, we may include incremental backups in a future release and will change the backup nights with no notice, so you must insert the diskette and boot the computer each evening.

A node which finds its GO file (PC$BACKUPS: nodename.GO) will proceed to do a full disk backup of all its disks using the MS-DOS XCOPY utility. The logical and physical disks to be saved need to have been previously declared.

(Note: inform Deb Baddorf if you change the number of hard disk partitions you have, or add another physical drive!)
A regular XCOPY command is used on the PC; the destination is a virtual disk file on the VAX created using DECNET-DOS. The virtual disk file will have the name PC$BACKUPS: nodename.drive (for example, PC$BACKUPS:EEDWRK.C). After these files have been copied to tape during the nightly VAX backup, they will be deleted from disk at 4 p.m. to make room for the next batch of PC's to do their backups the next night. After the node has done an XCOPY of drive C, D, E ... it will halt at the normal DOS prompt. You must boot in the morning from your hard disk to get your normal setup installed.

How to Restore:

You can do a directory of WARNER::PC$BACKUPS: nodename to see if, perchance, your virtual disk files are still online. They probably won't be, if it's been more than a day since your node backed up. In this case, you contact Deb Baddorf and ask for a file to be restored from tape. This takes about 2 hours. She'll need to know the nodename (e.g.: EEDWRK) and which drive(s) you need. The virtual disk file(s) you request will be restored to the VAX disk.

The VAX save tapes are re-used in a four week rotation. This means that you can only count on the saved virtual disk file existing for four weeks.

Please tell Deb as soon as you know you need a saved virtual disk file.
Don't wait until the replacement PC hard drive arrives, (for example); tell us which files you need right away so that we can be sure we save them from being overwritten on the tape. The four week rotation also means that it is important for you to remember to insert the diskette and boot every night. If you miss your turn too many times in a row, then we have no backup files for your PC and cannot help you recover lost work.

When the files are back on the VAX disk, you use the NDU program on the PC to open the desired VAX file as a virtual drive. You can boot up from your hard drive or, if you've lost the whole drive, you should be able to boot from the AUTOBACK diskette. Do:

   start up decnet (NETON or STARTNET, possible)
Where Note that you must have the DECNET-DOS programs running on your PC to use NDU.

Use the MS-DOS ``copy'' or ``xcopy'' command, or the Norton utilities to recover your file(s). Treat the virtual disk just like another drive, x:, which is read only. When done, type

(use the same drive letter, x) to close the virtual disk.

To Force a BACKUP Out Of Turn:

If you've done a lot of work and wish to force a backup right now, do the following. Log into your WARNER account. Type:
and answer the question ``PC nodename: '' with the name of the node to be backed up (ex: EEDWRK). Then insert the AUTOBACKUP diskette into the PC and a backup will begin when you boot the PC.

Error Handling:

Since the only observed failure modes of the AUTOBACKUP procedures leaves the PC awaiting input at the ``ABORT, RETRY or IGNORE'' prompt, the system currently does no error reporting. On nights when it is not their turn to backup, nodes will print to screen the following message:

A backup was not performed tonight.
The last line is the DOS prompt, designed to remind you that you are not running your normal system. On nights when the node does attempt a backup, successful completion will produce a message similar to the following:
Backup was performed tonight on node EEDWRK.
If you did not find an "ABORT,RETRY or IGNORE" waiting, then
successfully backed up drives C D E
Unfortunately, if there is a network error or a local error in reading the drive, the PC stops and prompts for terminal input. This case is recognizable by the lack of DOS prompt, and by the ``ABORT, RETRY or IGNORE'' message which will be waiting for input. If you find this message, you should probably FORCE a backup for the next night.

Supported Configurations:

DECNET-DOS will currently support only virtual disks which are strictly less than 32 Meg. We hope to get a fix to allow 32 Meg disks to be saved, but currently a 32M hard disk partition which is full enough will cause problems. Larger disk partitions will only be supported if future DECNET-DOS releases support them. We have AUTOBACK versions for PC's using the DMDRVR.BIN driver and for the 3-6 PC's using the DRIVEDEF and AUTO_DEF driver files.

Questions? Comments?

If there's anything I've forgotten to cover here, ask me! If your node is not set up to participate in this scheme, again, ask me! I need to create one file and one directory on your PC, but I also need to add your nodename to the list of known nodes on the VAX end. (Make sure I don't forget that part!)

Participating PC nodes are expected to be running DECNET-DOS version 2.1 or later. We can help in upgrading if your node is not up to this version level.

This is still an early version of the AUTOBACKUP program. (The version number is displayed in the DOS prompt.) This system will be evolving as we all gain experience with it. We look forward to your questions, suggestions, and bug reports.

Keywords: IBM, PC, backup, DECnet, MS-DOS, archive, tape


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