From: lee@dlpco.COM (Lee Penn)
Newsgroups: biz.sco.general
Subject: Tape backup revisited/CTAR/Tape verify
Date: 22 Jul 92 12:58:36 GMT
Organization: [resent by] The SCOGEN gateway and Propagation Society
Resent-From: mmdf@xenitec.on.ca
Submit-To: scogen@xenitec.on.ca
Precedence: bulk

OK...  Here is a disaster recovery story to charm everyone's 
technical hearts...

I have a new customer with a 386/33 Compaq SystemPro.  We 
installed a 486/33 processor board, used the latest greatest 
Compaq config program AND VOILA!!!!!!  The hard drive was 
trashed!  What was supposed to be a 15 minute quick swap out of 
CPU's turned into a 24 hour emergency recovery story.  Compaq 
told us that the new configuration program changes parameters on 
the IDA controller for faster processing.  Wasn't that nice!!!  
Of course there is no warning that the reconfiguration process 
was going to trash the IDA array!!!  BTW: Jeff Hill at SCO was 
extremely helpful to us in at least attempting to recover the 
situation.  But finally, we had to go to backup tapes.......

Did you know:

        1. IF there is a single bad spot on a tape, there appears 
                to be NO WAY to get past it.

        2. IF the previous consultant specified the WRONG number 
                of blocks (500000 instead of 250000) for the k 
                parameter of tar that the end of the 1st volume 
                might NOT be readable!!!

ON ALL of the customer's backups, it at first appeared to be 
impossible to read his PRODUCTION data as that production data 
was stored at the end of the 1st tape volume which we could not 
process.  Finally, in total desparation, I tried to recover ONLY 
the customer's production data directory and was able to recover 
their data as of close of business Thursday.  This was a last 
gasp attempt to recover data.  All other attempts had failed.

We tried the customer's original tape drive, an Archive tape 
drive, AND a Sankyo tape drive in attempts to read the data.  Our 
best guess is that the customer's tape drive (Wangtek) is not 
working properly and only "appears" to write data.  OF COURSE!!!!
the tape drivers do not pick up the fact that the device is not 
getting the tape data correctly, and just ASS-U-ME s that the 
backup is good!

BOTTOM LINE ON ALL OF THIS:

We desparately need better tape drivers from SCO and other 
UNIX vendors.  We need the ability to skip over bad blocks on the 
tapes.  We need the ability to skip to a specific track on a 
tape.  We need to be able to FORCE the tape drive to move further 
down the tape, past the bad data.

Even CTAR could not get past the bad spots on the tape.  It would 
ask about attempting error recovery, but could not get past the 
bad spots on ANY of the tapes.

VERIFICATION OF BACKUP DATA TO THE BIT LEVEL IS NOT JUST A FRINGE 
BENEFIT OF CTAR.  IT IS AN ABSOLUTE REQUIREMENT TO INSURE BACKUPS 
ARE 100% VALID.

DLP WILL NEVER SELL OR SUPPORT ANOTHER UNIX SYSTEM WITHOUT CTAR.  
WE FURTHER WILL NOT EVEN HELP A CUSTOMER WHO IS IN TROUBLE 
WITHOUT INSTALLING CTAR FIRST ON THEIR SYSTEM AND DOING VERIFIED 
BACKUPS.

DLP'S NEW LOGO:    "NO CTAR  -----   U DEAD!!!"


================================================================================
Lee Penn,  DLP Technologies, Inc.                     Voice: 513 232-7791
SCO Advanced Product Center                           FAX: (513) 232-7801
7444 Jager Ct.
Cincinnati, OH  45230-4344                           email: lee@dlpco.COM