how to backup archive log file when some old archivelog file lost

[稀里哗啦]

I have lost 2 archivelog file of 3 days ago.
After lost the 2 file, i can't backup other archivelog with rman at all. every time when i usung rman do backup, it alway say: "the losted" file can't found.
even when i use below command:
backup archivelog from time 'sysdate'

it also report integrity error.

I don't want using the way of "reset log" to resolve it, is there someone know other way?
Thank you.
B.R.

[Sanjay Kumar Suri]

Selected info from the link

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96566/rcmmaint.htm#454053

is listed below:

Run the CHANGE ... UNAVAILABLE command to mark a backup or copy as unavailable.

To mark a file's status in the repository as UNAVAILABLE:

1. Issue a LIST command to determine the availability status of RMAN backups and copies. For example, issue:
LIST BACKUP;
LIST COPY;


2. Run a CHANGE ... UNAVAILABLE command to mark a backup or copy as UNAVAILABLE in the RMAN repository.

For example, enter:
CHANGE DATAFILECOPY '/tmp/control01.ctl' UNAVAILABLE;

CHANGE COPY OF ARCHIVELOG SEQUENCE BETWEEN 1000 AND 1012 UNAVAILABLE;

CHANGE BACKUPSET 12 UNAVAILABLE;

CHANGE BACKUP OF CONTROLFILE UNAVAILABLE;
CHANGE BACKUP OF SPFILE TAG "TAG20020208T154556" UNAVAILABLE;

sks

[Brian Crabtree]

connect into rman (with catalog if you have it), and run the following command:

change archive all validate;

This will set the log unavailable if it is not there.

Thanks,

Brian