Re: Backing up physical files

>From: uunet!jjolly.b24a.ingr.com!jjolly (Jack G. Jolly) >Subject: Backing up physical files >Date: Mon, 23 Nov 1992 19:06:56 GMT >X-Informix-List-Id: <news.2181> >Is it necessary to back up the physical files associated with an >ONLINE db "outside of the environment"? Consider "raw partitions" as well. >I always thought that backup of physical files was a necessity to >prevent against disk failure - that you would restore your old >files and apply the contents of saved transaction log files against >them to bring them up to date (at least that is how you're supposed >to do it with Oracle). >Does the "Archive" utility in tbmonitor eliminate the need to make copies >of the physical files?? Provided that you are using the archive procedure built into the OnLine product (tbtape, possibly accessed via tbmonitor), you do not need to back up the physical disks outside the database environment. In fact, if you did do an external backup, it would be approximately worthless for either of the following reasons: * The backup would not be consistent unless the OnLine system was down while the backup was done. In contrast, the OnLine archive facility ensures a coherent backup of the database, despite any activity which is happening while the archive occurs. * It would not be safe to try rolling forward the database with any log files, so any transactions done after the backup would not be (reliably) recoverable. Again, in contrast, the OnLine archive is properly synchronized with the logical log backups, and therefore the recovery process can be extended up to the last completed transaction before the system failed and required recovery. Yours, Jonathan Leffler (johnl@obelix.informix.com) #include <disclaimer.h>