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Help me understand Multplexing

Justin_England
Level 3
OK. I have 4 servers
1 MSSQL server
1 webserver
1 appserver
1 testserver

I am wondering what I need to do to mulplex the back operation.

on my MSSQL server my DB is about 5 gigs, this database points to a RAID that is connected to the server that has about 1TB of space and about 1/2 is used. Now I have sceen when I setup my policy it consists of
8 jobs
4 system state jobs
4 Folder Operation jobs

I am wondering since 3 of the 4 folder operation jobs are about 10 gigs a piece and the 4th job is 500 gigs, can I get the 4th job to go onto differant drives???

How do I do it?
4 REPLIES 4

Vishal_Mehra
Level 3
You should be able to do this via policies and the storage unit configuration for mulitplexing. How many tape drives do you have?

Justin_England
Level 3
Yes -- I do have multiple drives -3 - but what I want is to know how to make the multiplexing work. I could not find documentation on how to make it happen. Please point me to Documentation that explains in detail how to make it happen

Thanks

Kezic_0
Level 3
Justin

There is some information in the Sys Admin Guides concerning Multiplexing however its does not go into the details very deep.

In your example if you would like to get 1 stream out of 4 to go to a different drive you would have to create a new policy and add the 500 GB folder to that policy and turn off Multiplexing for that specific policy.

I cant think of another way to do it. If you keep them all in the same policy and set the mpx value to 3 you wont be able to control what 3 streams start on the same drive and what stream goes to the second drive.

Hope that helps

kbadur
Not applicable
I am not quite sure if it is multiplexing you want - it sounds more like multiple streams per policy. Multiplexing aggregates several data streams from different clients/policies on the server side and writes them to the same tape. Multiple streams, on the other hand, take the backup selections specified in the policy and breaks them down to individual streams, each sent simultaneously to different drives. Multiplexing is usually only recommended if you are unable to feed a tape drive fast enough that it has to start and stop waiting for buffers from the clients - having several clients feeding the drive allows the backups to run more efficiently, but it also makes restores very slow because the multiplexed jobs have to be disentangled first. I have always found the tradeoff unfavorable, but it depends on your environment.

In your particular case, at least as far as I understand your description, multiplexing would not really have any advantages.

As the previous poster suggested, the best way to separate the last directory from the others is to create a different policy. If you were backing up a single client with several filesystems, you could use the NEW_STREAM directive in the backup selections dialog to generate multiple streams. For example, if you have the following entries in your backup selections

dir1
dir2
NEW_STREAM
dir3

the backup of this policy will create two jobs: One backing up dir1 and dir2, and the other will back up dir3, and the two jobs will run simultaneously (only if your jobs per client setting is set higher than 1, of course.) I never create policies with multiple clients, so I have no idea how you could do this in such a policy.

You could also simply try to allow the policy to create multiple data streams. Finally, you can combine this with multiplexing if you cannot feed tape drives fast enough.