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Restore issue

NBU_Adm
Level 3

our database team triggered rman restore with 4 channels, but 1 restore channel is running out of 4 and the remaining are ideal. Please let me know how to run 4 restore channesl at time and 4 channels are in different media.

we have engouh drives and enable media multiplexing, but only 1 streem is running.please let me know is there any way to make the other streams to run.

2 ACCEPTED SOLUTIONS

Accepted Solutions

RiaanBadenhorst
Moderator
Moderator
Partner    VIP    Accredited Certified

It depends how your data has been written. If you've used multiplexing to do the backup (which is not good) then you'll not be able to read 4 streams simultaneously.

 

If you've not written the backups with multiplexing, and you've used 4 drives to store the data on 4 media then you should not face this issue.

 

Please confirm.

 

Do the streams that are queued say something like "waiting for media xxxxxx" " media in use"?

 

What does the status inside those jobs say?

View solution in original post

Michael_G_Ander
Level 6
Certified

How many rman channels was allocated when doing the backup ? my guess would be one

You get the best performance if you allocate the same number of rman channels for the restore as the backup was written with. 

To restore from 4 different media, you need 4 channels writing to each their own tape drive when doing the backup, which means you cannot use multiplexing on the tape drives.

 

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue

View solution in original post

3 REPLIES 3

RiaanBadenhorst
Moderator
Moderator
Partner    VIP    Accredited Certified

It depends how your data has been written. If you've used multiplexing to do the backup (which is not good) then you'll not be able to read 4 streams simultaneously.

 

If you've not written the backups with multiplexing, and you've used 4 drives to store the data on 4 media then you should not face this issue.

 

Please confirm.

 

Do the streams that are queued say something like "waiting for media xxxxxx" " media in use"?

 

What does the status inside those jobs say?

Born2rise
Level 4
What does job detail showing for the restore jobs which are in queued? We will be able to help you if we know the reason of the job to be in queued

Michael_G_Ander
Level 6
Certified

How many rman channels was allocated when doing the backup ? my guess would be one

You get the best performance if you allocate the same number of rman channels for the restore as the backup was written with. 

To restore from 4 different media, you need 4 channels writing to each their own tape drive when doing the backup, which means you cannot use multiplexing on the tape drives.

 

The standard questions: Have you checked: 1) What has changed. 2) The manual 3) If there are any tech notes or VOX posts regarding the issue