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Recovery database in critical situation? Expand / Collapse
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Posted Tuesday, August 12, 2014 7:06 AM
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Hi,

I want to know about database recovery in critical situation.

Configured full back-up on daily basis at 12:00 PM.

1. I have full back-up on Monday and followed by Transaction log

2 .Unfortunately I missed Tuesday full back-up. But I have transaction log till Tuesday at 3:00 PM.

Server was some issues at 3:30 PM, and data file not able to access due to disk level corruption happened and not able to take backup also.

In this scenario, how can we recovery database in point-in-time?

Thanks
ananda
Post #1602270
Posted Tuesday, August 12, 2014 7:22 AM


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Do you have every single transaction log backup from the Monday full backup up to now? Every single one without a gap?
Has the database been set to simple recovery at any point between the monday full backup and now?



Gail Shaw
Microsoft Certified Master: SQL Server 2008, MVP
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Post #1602278
Posted Tuesday, August 12, 2014 11:31 PM
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Let me explain more details about data recovery in critical situation

As per backup Plan
1. Daily one Full backups at 12:00 AM configured
2. Every 30 minutes Transaction log backup configured

Critical situation 1

I have two set of full backup file (Monday and Tuesday) and on Tuesday transaction log backup file available till at 3:00 PM

On Tuesday, Server was some issues at 3:30 PM, and database not able access also not able take Tail log backup at event of server failure.

In this scenario, how can we recovery database in point-in-time?
For the data recovery, first restore Tuesday full backup and followed restore the all TLOG backup file till 3:00 PM.
So we accepted 30 minutes data loss and can able to restore the data till 3:00 PM only. Am I correct?

Critical situation 2

1. Unfortunately Tuesday full backup file missed.
2. Monday I have all transaction log backup and Full back-up, on Tuesday I have only transaction log backup’s till 3:00 PM.

On Tuesday, Server was some issues at 3:30 PM, and data file not able to access due to disk level corruption happened and database can accessible. But not able to take full and Tail log backups

In this scenario, how can we recovery database in point-in-time?

For the data recovery, LSN chain was broken due to Tuesday full backup. So how can restore the Tuesday TLOG backup’s files on followed by restore the Monday full backup.

Thanks
ananda



Post #1602567
Posted Wednesday, August 13, 2014 12:55 AM


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Case 1, correct. If you can't take a tail-log backup, then you can only restore to the last log backup you have.

Case 2, Full backups DO NOT and NEVER have broken the log chain. Ever. Restore Monday's full then all log backups up to the last one you have.



Gail Shaw
Microsoft Certified Master: SQL Server 2008, MVP
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Post #1602587
Posted Wednesday, August 13, 2014 1:37 AM
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Thank you for confirmation,

Case 2. we can restore point in time recovery by using perivious day full backup also apply all second day tlogs backups file even if lost second day full backup.

So in this case 2. I have to take care all Sequential log backup files. so i could't resotre point in time If log chain broken between.

what could be reason log chain will be broken?
Post #1602601
Posted Wednesday, August 13, 2014 2:13 AM This worked for the OP Answer marked as solution


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SQL Galaxy (8/13/2014)
what could be reason log chain will be broken?


Missing log backup file (deleted) or the DB was switched to simple recovery sometime during that time period.



Gail Shaw
Microsoft Certified Master: SQL Server 2008, MVP
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Post #1602609
Posted Wednesday, August 13, 2014 5:21 AM
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In such critical situation you must go with reliable and effortless recover tool.
Post #1602663
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