Question

SQL DB LiveSync On SubClient Level


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Hello All,

One of customer wants to run SQL LiveSync from T-log backups. They have couple of question related to same.

 

  1. With “Stand By” option and running live sync continuously, at the moment when Live Sync is running the restore from a T-log, will any exiting queries to read the data from the target databases be affected?
  2. Can we put blackout window on LiveSync (Replication Job) ?
  3. Can we schedule Live Sync to run from 8 AM to 5 PM daily? If so, will it pick up all the T-logs between 6 PM and 7 AM to restore to the target databases as soon as we resume the LiveSync again ?
  4. Will there be any IOPs or network bandwidth issue when we run live sync for 4000+ databases at the same time?

 

 


3 replies

Userlevel 6
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Hello @Rohith Sharrma 

  1. No should not be an issue
  2. Yes you can use blackout windows
  3. not a specific schedule like that but can use as backup completes with blackout window
  4. Yes but too many variables to tell. network bandwidth would be size of backups and IO yes SQL has to play back alto of logs for 4000+ dbs.
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Hello @Scott Reynolds 

I got the answer from support but they seem to contradict yours. Below are the answer i got from them.

 

  1. Commvault API will not touch any target databases. Let's Suppose, if you are performing a Backup for two databases on source server and same are being replicated to destination server, no other databases will be touched on destination server when the Live Sync is running
  2. No, it will not pick all the T-Logs between 6 PM and 7 AM to restore to the target databases, it will only pick the latest one and probably that would be from 7AM or depending on the schedule
  3. It is sequential process.
  4. It might mark the job as completed with error in case DB's are no longer available on existing role, thought it better to test and confirm
  5. It May have IOPs or network bandwidth issue
  6. CV Cant Put Blackout window on LiveSync Replication Jobs.

 

@Scott Reynolds  Though I have one more question now. When we perform LiveSync replication job, is there a record on which database was picked up first when each LiveSync job gets started ?

@Staline Please update in case you have any idea about my question above ?

 

Userlevel 6
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@Rohith Sharrma 

Can you please share with me TR number?

Most of the answers line up with my answer. Will confirm on blackout window and livesync.

For 3. Whenever live sync runs time it runs does not matter it will restore ALL logs backups that have NOT be restored to the destination DB. 

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