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mahajanakhil1985
Yak Posting Veteran
71 Posts |
 Posted - 2010-08-23 : 08:40:21
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| As checkpoint truncates the inactive portion of the transaction log, then what will happen to this portion of the log which is yet not backed up by the Backup job on the primary node? Will the transactions corresponding to this portion of the log be not applied to the secondary node? |
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tkizer
Almighty SQL Goddess
38200 Posts |
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mahajanakhil1985
Yak Posting Veteran
71 Posts |
Posted - 2010-08-23 : 12:57:46
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| Yes, ideally it happens or it should happen. But how does it respect the definition of checkpoint? Checkpoint truncates the inactive portion which is not yet backed up, then how could it be that it skips that portion and then starts backing and applying the the transaction logs to secondary node after the checkpoint? |
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tkizer
Almighty SQL Goddess
38200 Posts |
Posted - 2010-08-23 : 13:12:20
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You are confusing terms. A transaction log backup is what truncates the inactive portion of the log. A checkpoint is different. Here's a good article: http://www.craigsmullins.com/ssu_0600.htmAnd here's some info from an MSDN article:quote:
If log records were never deleted from the transaction log, it would eventually fill all the disk space that is available to the physical log files. Log truncation automatically frees space in the logical log for reuse by the transaction log.Except when delayed for some reason, log truncation occurs automatically as follows:Under the simple recovery model, after a checkpoint.Under the full recovery model or bulk-logged recovery model, after a log backup, if a checkpoint has occurred since the previous backup. For more information, see "Log truncation under the full and bulk-logged recovery models," later in this topic.
Tara KizerMicrosoft MVP for Windows Server System - SQL Serverhttp://weblogs.sqlteam.com/tarad/Subscribe to my blog |
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mahajanakhil1985
Yak Posting Veteran
71 Posts |
Posted - 2010-08-27 : 08:52:03
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| "Under the full recovery model or bulk-logged recovery model, after a log backup, if a checkpoint has occurred since the previous backup."This is what I could not understand, probably the organization of phrases.Suppose a backup A is taken at 10 am and a backup B is taken at 11 am. Does the above statement in quotes mean that the inactive portion of log will be truncated after taking the backup B at 11 am if a checkpoint has occurred between backup A at 10 am and backup B at 11 am?Or , does it mean that the part of transaction log that has entries before 11 am will be truncated when first checkpoint occurs at any time after log backup at 11 am and the log entries after 11 am will remain intact? |
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log shipping doubt