RE:informix log backups

HI, =20 I have a particular question about transaction logs which get backed up using ontape. =20 I know that you can do a... =20 Physical backup & restore (which is a backup/restore of a dbspace(s) or blobspace(s) Logical backup & restore (which is a backup/restore of a logical space(s)) =20 My question is do you always have to back up logs regardless of whether there are no sql executed which performs rollbacks and commits? =20 I ask this because as a DBA with a Sybase background I know that we did a full backup of a database as well as backed up the transaction logs. However I am sure that whether you performed a commit or rollback command or not it was all stored in the transaction logs so that in the event of failure you restore the full backup and then restore the transaction log backups up to the time of the failure or corruption so that your database had the changes made after the full backup was done. =20 Otherwise what would be the point of the logs? =20 I look forward to your reply. =20 L =20 Lee Aholima, Database Administrator Thames Coromandel District Council Ph 07 868 6025 Email lee.aholima@tcdc.govt.nz Mobile 0274333915 =20

Hi, you are right. It works the same way with IDS when using ontape. I don't know Sybase [ well I know the name ... :-) ], so I point out a couple of things here : - When using ontape for backups/archives you can: - do level 0 , 1 and 2 archives, - backup logical logs, - decide to not backup logical logs at all. - During restore you can : - do cold and warm restores. Cold restores are mandatory for so called critical dbspaces, warm restores can be done on non-critical dbspaces. [ You may want to check manuals for critical vs. non-critical. ] - For cold restores you start with a level 0 archive, you can then decide whether to restore further level 1 and level 2 archives (if you've taken any). After that, if you decide to not restore logical logs, you will get a system of the time when the latest archive that you restored was taken. It will be consistent as open transactions will be rolled back (even though no logs were restored). - After the archive(s) restored (aka physical restore) you can restore logical logs (provided you backed them up) to roll forward transactions that were done after the latest archive was taken. When the last log has been restored, open transactions will be rolled back and you also get a consistent system. However, using ontape you cannot really do a Point In Time (PIT) restore, i.e. tell it to restore logs and rollforward their records only up to a specific PIT. (Not sure if you're used to that in Sybase.) ontape will ask each time it has processed a complete log TAPE for a new one. You can always stop at that point. This makes granularity of log restore by LOG TAPE rather than by log record. (Several log files containing many log records may be on a single log tape.) [ In case you really need the PIT restore functionality, then you'd have to use ON-Bar, another archive/backup and restore tool. But it has it's own manual ... :) ] Regards, Martin -- Martin Fuerderer IBM Informix Development Munich Data Management Solutions "Lee Aholima" <lee.aholima@tcdc.govt.nz> Sent by: forum.subscriber@iiug.org 11.04.2003 05:44 To: ids@iiug.org cc: Subject: RE:informix log backups [897] HI, =20 I have a particular question about transaction logs which get backed up using ontape. =20 I know that you can do a... =20 Physical backup & restore (which is a backup/restore of a dbspace(s) or blobspace(s) Logical backup & restore (which is a backup/restore of a logical space(s)) =20 My question is do you always have to back up logs regardless of whether there are no sql executed which performs rollbacks and commits? =20 I ask this because as a DBA with a Sybase background I know that we did a full backup of a database as well as backed up the transaction logs. However I am sure that whether you performed a commit or rollback command or not it was all stored in the transaction logs so that in the event of failure you restore the full backup and then restore the transaction log backups up to the time of the failure or corruption so that your database had the changes made after the full backup was done. =20 Otherwise what would be the point of the logs? =20 I look forward to your reply. =20 L =20 Lee Aholima, Database Administrator Thames Coromandel District Council Ph 07 868 6025 Email lee.aholima@tcdc.govt.nz Mobile 0274333915 =20