dd command

[Ngoh Chean Siung]

Hi,

Is there anyone familiar to dd command? I want to restore informix archive level 0 with roll forward logical logs.

I have a informix logical logs tape. I wish to extract it into a file by using dd command.

This file will consists of logical logs which is in hexadecimal format.

My problem is when I try to dd the logical logs into a file, it seems like not all the logical logs has been extracted.

Just want to know how to play around with bs. I try to use bs which is 1024k, 2k, 2048 & 4096k. Hv try with the bs but still same. Actually what is the bs that I should use?

regards.

[Bharat Katkar]

Hi,
Not sure about it but just see if the link below helps you out.

http://forums1.itrc.hp.com/service/forums/bizsupport/parseCurl.do?CURL=%2Fcm%2FQuestionAnswer%2F1%2C%2C0xd317543254bfd611abdb0090277a778c%2C00.html&forumId=2&admit=716493758+1098346134989+28353475

Regards,

[Simon Hargrave]

If it's reading something, then block size shouldn't really make a difference, except in performance terms, as in how fast data is transferred from tape.

Are you sure dd is the actual command you want to use, were the logs just dd'd to the tape?

I don't have any experience with Informix, however the linked page below suggest a tool called ontape is used for Informix?

http://examples.oreilly.com/unixbr/informix.html

[Rainer von Bongartz]

What does lead you to the conclusion that you cannot extract all the logical logs ?


Regards
Rainer

[Ngoh Chean Siung]

Hi,

I have a informix archive level 0 with log id 40701 and a informix logical logs with log is 40586 until 40843.

I wish to restore it with archive level 0 and roll forward to logical logs 40799.

So, I have to use dd.

First step
dd if=/dev/rmt/1m of=ltape bs=1024k
=> This is to extract all the logical logs inside the tape to a file called ltape.

Second step
xd ltape | egrep -e"^....... ffff ffff" > xddumb.txt
=> This is to perform a hexadecimal dump & pipe to a file called xddumb.txt

Third step
By right, inside this file, I managed to see the logical tape header (which is indicated as "0009" in first row and column number 7) and logical tape trailer (which is indicated as "000a" in the last row column number 7).

But, this file seem doesn't have any logical tape trailer.

Is anyone who have try to restore informix archive level 0 with roll forward logical logs?

regards.