We run Retrospect 4.2 to backup about 70 Macs over 4 
different appletalk zones to 12GB (24GB) DSS tapes. We don't backup 
any PCs but we experience vaguely similar problems over the past few 

        The backups became intolerably slow (sometimes averaging < 
8MB/min!) so we upgraded the backup computer to a beefier mac and 
shifted the process to an external drive from which the computer 
boots, runs retrospect and keeps the catalogues (this was to make 
future upgrades easier).

        The backups speedup to a comfortable average of about 
35-40MB/min on average. Currently they take about 12-13hrs so this is 
filling about 1.3 tapes worth...meaning we have to switch tapes in 
the morning and then add the clients that we missing or out of action 
the night before.

        The major drama now is the discovery that the backup server 
was the one that was bringing down the email server each night (same 
zone different computer). This lead us to a serious investigation 
revealing that although all our clients are using tcp/ip not 
appletalk retrospect appears to cause major collisions on the network 
resulting in computers that are actively using appletalk (namely the 
email server/DNS server) dropping it's appletalk connection. In which 
case nothing can find it (tcp/ip or appletalk) on the network. You 
need to restart it or switch the appletalk connection to a different 
port and then back again to ethernet....ahhhh!

        I'm not 99% sure it's retrospect causing it, but I've tried 
the following to narrow it down:

Changed IP address: no result
Changed E'net ports: no result
Changed E'net cards: no result
Changed system (8.1--> 8.5): no result
Changed system (8.5--> 8.5.1): no result
Changed system (8.5.1--> 8.6): no result
Checked and cleaned extensions: no result
Booted from a seperate drive to retrospect: no result
Backed up to a drive instead of tape: no result
Changed computers (same extnl drive): no result
Reinstalled retrospect: no result
Tried 4.0, 4.1i and 4.2: no result

(Not tried yet):
Move the computer to another zone.

Now here's the weird part:

Retrospect clients, as mentioned earlier, are using the TCP/IP 
protocol stack, same as Netscape does when you surf the Internet from 
the Backup server (just as a test). However, surfing the net causes 
no collisions, but retrospect redlines the collisions.

Also even an appletalk copy will set collisions off....so where is 
the consistency?

If anyone knows of a similar case, a possible cause and if luck would 
have it a solution to the problem please respond ASAP.


>We run a series of nightly backups using Retrospect 4.1A, backing up
>around 20 Mac's and 20 Win98 PC's.  Ever since the Windows backups
>were added, we've experienced occasional crashes of the backup Mac.
>Often this has been accompanied by corrupted catalogues (chunk
>checksum errors).
>After months of studying it we have found one reproducable problem:
>if someone shuts down or reboots one of the Win98 PC's while it is
>being backed up, the backup Mac will often crash.  We also have other
>problems backing up the Windows boxes, with network communications
>failures on different slower PC's regularly.  At first some of PC's
>were Win95 so we thought that was part of the problem.  But we've
>now upgraded all of them to Win98 and the symptoms are still occuring.
>There are no other network related problems on these boxes; we
>use file sharing fine and uses regularly utilize Netscape to access
>the 'net over tcp/ip connections through a router.  All is fine there.
>In summary:  has anyone experienced problems with Mac crashes when
>backing up Win98 PC's and/or regular "network communications failed"
>and/or "chunk checksum errors"?  Thanks!
>| Computronics                   Randy Styka, [EMAIL PROTECTED] |
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