[comp.sys.apollo] Deteriorating Media

markl@neptune.AMD.COM (Mark Luedtke) (09/07/89)

We have a dsp3550 with two 760Mb drives.  A couple of weeks ago we had the
primary drive replaced as disk data check errors were occuring at an increasing
frequency.  When we went to load the user data back, we found our backups were
not complete, so we had our Mentor representative install the disk in one of
his machines and dump a tape (they use cartridge almost exclusively).  Well,
after getting the tape here, we couldn't read beyond some tape error to get at
the two projects we need restored.  The rep then had problems writing another
tape.  Now the drive is reinstalled here, but it won't mount since the logical
volume header appears to be corrupted.

Question #1:
Does anyone know of a way to get at the data on the tape (probably the better
copy)?  RBAK dies at some location and will not find anything further, but if
I could get it to start looking further down, I should be able to access the
data.  An index, using RBAK, will pass the bad spot, but reading won't and
using '-f cur' tells me that the current location is unknown.  Can I use RWMT
in raw mode to build a file then RBAK from that file?  Any options at all
for the tape?

Question #2:
I'm sure most of the data is still on the disk, but how can I get to it?
Using fixvol I can get make the PV ok, but the LV and ALV are trashed (disk
data check again).  I also tried using UNIX mkdisk with mount and dd, but
dd only read what appeared to be some header information then quit with no
error message; mount claimed the volume was in use.  Any suggestions for
dumping the disk?

We are running 9.7.5 and the machine is mounted diskless off a dn3550.  We
also run BSD4.2, and I could probably install SYS V if it would help.  Any help
is appeciated.

Mark Luedtke    markl@neptune.amd.com    (512)462-5278

Disclaimer (?) My spelling is a work of art

rchrd@well.UUCP (Richard Friedman) (09/09/89)

In article <1082@neptune.AMD.COM> markl@neptune.AMD.COM (Mark Luedtke) writes:
>
>Question #1:
>Does anyone know of a way to get at the data on the tape (probably the better
>copy)?  RBAK dies at some location and will not find anything further, but if
>I could get it to start looking further down, I should be able to access the
>data.  An index, using RBAK, will pass the bad spot, but reading won't and
>using '-f cur' tells me that the current location is unknown.  Can I use RWMT
>in raw mode to build a file then RBAK from that file?  Any options at all
>for the tape?
>
Welcome to the unreal world of the small machines!  On all mainframe systems
there is a way to read tape ignoring (but flagging) errors, or to read past
partity errors, or some such thing.  As  far as I know and have seen there
is nothing like that available with RBAK (or tar)  This is very serious!
As you found out, you cant rely on your backups being readible!
Apollo really needs to address this problem with some sort of fail-safe
options on rbak or tar.

I suspect some of the high-powered users might have written their own
polish-off-the-tape-and-read programs of their own to replace rbak.
Anyone know of any???
-- 
 /s/ rchrd <=> Richard Friedman <=>  rchrd@well
 rchrd@well.sf.ca.us | {apple,pacbell,hplabs,ucbvax}!well!rchrd
 [Pacific-Sierra Research / Berkeley CA] (415) 540-5216
 (The usual disclaimers apply - I speak only for myself!)

brock@tuvie (Inst.f.Prakt.Info 1802) (09/11/89)

In article <13518@well.UUCP> rchrd@well.UUCP (Richard Friedman) writes:
>In article <1082@neptune.AMD.COM> markl@neptune.AMD.COM (Mark Luedtke) writes:
>>Question #1:
>>Does anyone know of a way to get at the data on the tape (probably the better
>>copy)?  RBAK dies at some location and will not find anything further, but if
>>I could get it to start looking further down, I should be able to access the
>>data.  An index, using RBAK, will pass the bad spot, but reading won't and
>>using '-f cur' tells me that the current location is unknown.  Can I use RWMT
>>in raw mode to build a file then RBAK from that file?  Any options at all
>>for the tape?
/systest/ssr_util/cptape should help
Ulrich

petrost@prism.cs.orst.edu (Tony Petrossian) (09/13/89)

While you are on the subject (backups):

I was told today, that I need to start backing up the apollos
for EE department.  I have never used an apollo and dont
know much about them but I have been told that dump and rdump 
are not supported. Is there a way to do remote backups to
a remote tape drive?


I really dont want to use tar and pipes, and since I dont have
an account yet I could not RTFM about other alternatives.

I will appreciate any helpful hints.

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InterNet:  petrost@CS.ORST.EDU			Tony Petrossian
UUCP:      hp-pcd!orstcs!petrost		Computer Science
						Oregon State Univ.
						Corvallis OR. 97331	
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