SUMMARY: Backup Verification

From: Bill Evans (evans@c4west.eds.com)
Date: Fri Nov 08 1991 - 05:43:03 CST


Only three responses so far. The third look like it would work (haven't tried it yet).
I have SUN coming out to talk about a new backup software product. It sounds like
what I'm looking for, but until I see and try... I will send info on the SUN product
after evaluating it, but I didn't want to delay the summary.

Original message:

> We are using dump (primarily) to backup about 30 Sparcs here and would
> like to *verify* that the tape actually contains something without having
> to manually do a restore. The -v (verify) option in dump would work,
> except our file system is *almost* never quiescent.
>
> Are there any sucessful (tried and true) backup packages that are smart
> enough to know that the backup actually worked, but allow for (or report)
> any differences. Dump will fail the verification when it runs into the
> first changed or added file. I will summarize the replys to the net.

*******
From: Jay Plett <uunet!Princeton.EDU!jay>

Fetch the 4.4BSD version of restore from uunet or some other
archive site. It has an undocumented option which, I think,
will read a dump image without restoring it. You should review
what it actually does; I haven't tested it, but it looks like
that is what it does.

*******
From: uunet!lpi.liant.com!plott (Peter L. Ott)

I don't know what type of drivers you're using (Sun, Delta), but
we use Delta and we have written a script that will reserve a
block of tape for a table of contents, perform the dump, and then
do a restore -t and write it to the block of tape reserved for the
TOC. This TOC is then mailed to the operator. Fairly simple.

*******
From: uunet!adobe.com!weaver (Ron Weaver)

        I use a script that uses dd to verify the number of blocks written
to a tape. The 8mm & 4mm drives I use hold over 2 GBytes of data. Each
partition dumped using dump is a separate file on the tape. My dump script
counts the blocks written and I compare that to the listing I get from my
dump script.

e.g.
                SYSTEM PARTN. LEV. FILESYSTEM % tape BLOCKS TAPE
        Sun Oct 27 15:30:32 PST 1991 viafont0 067
        1 viafont rid000a 9 (/) 0.00 1002
        2 viafont rid000g 9 (/usr) 0.00 248
        3 viafont rid000h 9 (/home) 0.08 257532
        4 viafont rid001h 9 (/home2) 0.00 1236
        Mon Oct 28 06:39:03 PST 1991 viafont0 067
        5 viafont rid000a 9 (/) 0.00 1006
        6 viafont rid000g 9 (/usr) 0.00 248
        7 viafont rid000h 9 (/home) 0.08 257532
        8 viafont rid001h 9 (/home2) 0.00 1236
        Tue Oct 29 00:04:32 PST 1991 viafont0 067
        9 viafont rid000a 9 (/) 0.00 1154
        10 viafont rid000g 9 (/usr) 0.00 248
        11 viafont rid000h 9 (/home) 0.08 257586

Running the script (shown at the end of this message) produces
the following output. Note that the "records" truncates the
last two characters of the "BLOCKS" from above.

Wed Oct 30 07:30:03 PST 1991
host: viafont
program: 8mmck_0
number of files: 11
tape label: 8mmINC-067
utilization: 398862 Kbytes
    Checking file 1:
10+0 records in
10+0 records out
    Checking file 2:
2+0 records in
2+0 records out
    Checking file 3:
2575+0 records in
2575+0 records out
    Checking file 4:
12+0 records in
12+0 records out
    Checking file 5:
10+0 records in
10+0 records out
    Checking file 6:
2+0 records in
2+0 records out
    Checking file 7:
2575+0 records in
2575+0 records out
    Checking file 8:
12+0 records in
12+0 records out
    Checking file 9:
11+0 records in
11+0 records out
    Checking file 10:
2+0 records in
2+0 records out
    Checking file 11:
2575+0 records in
2575+0 records out
    Finished checking files. Rewinding tape...

dd script follows:

#! /bin/csh

#########################################################################
# "8mmck"
# DESCRIPTION
# script for checking the readability of tapes by using "dd" with a
# block size of 100b.
# The number of files to check on the tape can be entered on the
# command line, the default is 1 file.
#
# REVISION LOG:
# 12/08/87 initial version by bob wrucke
# 5/05/89 version revised by Ron Weaver
#########################################################################
# commonly changed variables
set tapedrive = /dev/nrst0 # no rewind

# process command line
if ($#argv == 0) then
        set files = 1
else
        set files = $argv[1]
endif

#check the tapes
set count = 0
while ($count < $files)
        @ count++
        echo ' Checking file '$count':'
        dd if=$tapedrive of=/dev/null bs=100b
        # Use the version of dd below for dumps made on Suns where 6250 density
        # is specified on the command line: example ( dump 0d 6250 /dev/xy0a )
        #dd if=$tapedrive of=/dev/null bs=64b
end
echo ' Finished checking files. Rewinding tape...'
mt -f /dev/rst0 rewoffl

****** END



This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:06:17 CDT