July 18, 2007 at 9:20 am
I've been working with ORACLE for years and over the last year have moved to SQL server 2005. The company I work for uses Legato as their backup solution. When performing a full backup the transaction logs are backed up with the database to the same set of tapes. Our backup admin says there is no way to separate the logs from the db and push them to two different pools using Legato.
This seems to be a flaw with Legato in my book. If you don't have enough time to make a copy of the backup tape before it goes off site you lose the opportunity to verify the data was backed up with out error. If that tape is corrupt or lost then you will not be able to recover from a previous full backup and restore all transaction logs. In ORACLE you can take a full backup from 3 months ago and as long as you have all the archive logs restore to any point in time. With Legato's methods you need to use the last full backup tape for a restore otherwise you can only restore up to the missing/corrupt full backup tape.
Anyone familiar with Legato and know a work around? Thank you for your assistance.
July 19, 2007 at 4:25 am
I am not sure if i understood your question correctly. But
1. If you are taking the database files to tape without taking a db backup then you might need the log file to redo and undo else you will lose data
2. if you have taken a db backup then it will have the log backup to within itself
3. if you have taken tlog backups separately then you need to take them to tape to recover
if i have understood your question wrongly then let me know.
Cheers,
Sugeshkumar Rajendran
SQL Server MVP
http://sugeshkr.blogspot.com
July 19, 2007 at 8:32 am
Sorry. For clarification. My company does a 'full backup' nightly. However, due to the amount of backups for all of our systems there is not sufficant time to run a varify on the backup. A Legato 'full backup' appends the transaction logs to the same set of tapes that the database is backed up to. The problem with this methodolgy is that if there is no time to run a varify and the tape has errors or the is perhaps lost then performing a restore of the previous days backup and rolling forward with the logs would only allow you to roll forward to the backup of the missing tape due to the missing transaction logs on the errorness/mia tape.
Monday - 00:00 - full backup
Tuesday - 04:00 - tlog backup
Tuesday - 08:00 - tlog backup
Tuesday - 12:00 - tlog backup
Tuesday - 16:00 - tlog backup
Tuesday - 20:00 - tlog backup
Tuesday - 00:00 - full backup (Errorness/MIA tape)
Wednesday - 04:00 - tlog backup
Wednesday - 08:00 - tlog backup
Wednesday - 12:00 - tlog backup
Wednesday - 16:00 - tlog backup
Wednesday - 17:00 - Corrupt database
In the timeline above you would restore the 'full backup' from Monday - 00:00 - full backup, but would only be able to roll the logs through Tuesday - 20:00 - tlog backup due to the logs being appended during the Tuesday - 00:00 - full backup (Errorness/MIA tape) backup. Essentially losing a days worth of transactional data.
Hope this makes more sense. I'm hoping there is a way to separate the tlogs to a different disk/drive pool during the Legato 'full backup'. Using SQL Enterprise Manager you can. Please see the attached link: http://msdn2.microsoft.com/en-us/library/ms189596.aspx
Regards,
Michael
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