On 16 Aug 2000, at 8:40, Yarmas, Tom wrote:
The Snapshot technology simply gives the DBA a virtual online copy of the datafiles that are stored on the Filer. There are many parts of the Oracle database, and many variations on which parts any individual might store on a Filer for any given Oracle Instance. It is important that no parts that are required for recovery are forgotten during a backup.
-tom
I can't agree more! Don't miss anything during a hot backup - get everything possible.
Over the years our backup system has developed around this problem. It's to the place I even backup some operating system stuff as part of the a hot bkup (/etc, crontabs, $oracle_home/dbs, $oracle_home/network/admin).
I haven't changed our hot backups to use snapshots yet, and probably won't for the near future. Our current hot backup script could be easily modified to handle snapshots, it's just that snapshots wouldn't gain us much in our current environment (db's on netapps aren't that big - yet).
Anyway, here's the highlevel outline of our hot backups. It creates a selfcontained hot backup that can be moved to another system and installed. We have other processes to handle archive logs. Our goal was to actually prove all hot backups by copying them to a special test sytem, install the hot backup and bring it up (all automatically) - . . . . never got that far . . . .
1) query db for all tablespaces 2) for each tablespace, determine db files 3) force a log switch 4) for each tablespace (handles multiple tablepsace concurrently) 4.1) put into hot backup mode 4.2) copy/compress files (we backup to local disk - tape backup system just backups the local disk area) 4.3) take out of backup mode 5) force log switch 6) copy logs created during hot backup (between log switches) to the hot backup area 7) copy the redo log files 8) "alter database backup controlfile to '/xyz/control.file.backup' ", save the file 9) copy all control file to the backup area 10)"alter database backup controlfile to trace", save the trace file 11) determine dump destinations and note them in the hot backup 12) backup "stuff" 12.1) /etc 12.2) crontabs 12.3) $ORACLE_HOME/dbs 12.4) $ORACLE_HOME/network/admin
(We also create a basic restore script during all of this.)
To use snapshots all I'd need to do is replace item 4 with the following:
w) put all tablespaces in backup mode x) issue snapshot y) end backup mode for all tablespaces z) copy/compress all db files from snapshot area to backup area.
As was stated in another email, snapshots don't really change how you do hot backups, just where/when you do certain things.
Rick