When i start my hot backup my database getting very slow

Question

Hi,
I am using following commands for enabling hot backup
SQL>ALTER SYSTEM ARCHIVE LOG CURRENT;
SQL>ARCHIVE LOG LIST;
SQL >ALTER DABATBASE BEGIN BACKUP;
Database altered.
SQL>SELECT FILE#,STATUS FROM V$BACKUP;
FILE# STATUS
1 ACTIVE
2 ACTIVE
3 ACTIVE
4 ACTIVE
and using cp -rp command to copy the file (backup copying speed good) but database performance very slow
How to improve performance ...
Regards
Vignesh C

Answer 1

Uwe Hesse wrote:
It is very likely that you experience slow performance with ALTER DATABASE BEGIN BACKUP , because until you do ALTER DATABASE END BACKUP , every modified block is additionally written into the online logfiles . Doesn't that happen only the first time the block is modified?
>
The command was introduced for split mirror backups, when this period is very short. Else ALTER TABLESPACE ... BEGIN/END BACKUP for every tablespace one at a time reduces the amount of additional redo during non-RMAN Hot Backup. There appear to be only 4 files. We don't know how big or sparse they are.
>
RMAN doesn't need that at all - much less redo - and also archive - generation then.
Furthermore, you can use BACKUP AS COMPRESSED BACKUPSET DATABASE to decrease the size of the backup even more - if space is an issue.
In short: Use RMAN :-)
Agree with that! Unless the copy is actually going to an NFS mount or something, where I would be concerned whether it is the type of NFS that Oracle likes. I'd also advise a current patch set, as the OP didn't tell us the exact version, and I have this nagging unfocused memory of some compression problems of the "oh, I can't recover" variety.
I'd like to see some evidence on I/O and cpu usage before giving advice. When I used to copy files like this, it would choke out everyone else. RMAN was a savior, but had to wait for local SAN upgrade.