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Replication is consuming all bandwidth

Hi experts, We are facing issue in our environment where replication is set between 2 netbackup domain having appliances. When replication is running sometime network team is complaining high outbound usage from appliance. Please suggest what is causing such issue. The mpls link is 30mbps between 2 sites and there is not more than 10-15 replication jobs running simultaneously. Nb ver : 7.6.2 Appliance :5230 Urgent help required
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Accepted Solution!

As Nicoli pointed out,

As Nicoli pointed out, replication takes all the available bandwidth since it does not know what is available until you tell it. You can throttle the bandwidth in one of two methods the one I am going to recommend is the one using the agent.cfg located in /disk/etc/puredisk. If you set the bandwidth to a KBps setting that you would like to use things should be well. 

The issue is NBU uses KiloBytes and networking uses KiloBits so some math is involved. In your case you have a 30Mbps link (3840KBps [(30/8)*1024]) and you want to use only 20Mbps for replication. you would calculate the 20Mbps change to KBps by dividing the 20 by 8 to get MBps (2.5MBps) and then multiply that by 1024 to get KBps (2560KBps). Edit the agent.cfg and locate the bandwidth=0 location and change that to 2560. The very next time the replication process checks the agent.cfg for that setting the bandwidth will change for that job eventually all jobs conform.

The reason I recommend this method is because you will always use the 20MBps regardless of how many jobs you have running. If you use the second method you will need to calculate how many potential jobs you would be running and then set the OPDUP_BANDWIDTH setting to the 20Mbps divided by the potential amount of jobs and that is what will be used PER job regardless of the number running. If you set OPDUP_BANDWIDTH to 124 KBps and only one job was running then that job would use only 128KBps. With the agent.cfg model you would use all 20Mbps if you had only one job

A more in depth understanding can be seen in the Deduplication administrator's guide http://www.symantec.com/business/support/index?page=content&id=DOC6466 look around page 86.

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5 Replies

Hi, The replication will

Hi,

 

The replication will take all the bandwidth you give it. How much data was backed up and has to be replicated?

 

 

Accepted Solution!

As Nicoli pointed out,

As Nicoli pointed out, replication takes all the available bandwidth since it does not know what is available until you tell it. You can throttle the bandwidth in one of two methods the one I am going to recommend is the one using the agent.cfg located in /disk/etc/puredisk. If you set the bandwidth to a KBps setting that you would like to use things should be well. 

The issue is NBU uses KiloBytes and networking uses KiloBits so some math is involved. In your case you have a 30Mbps link (3840KBps [(30/8)*1024]) and you want to use only 20Mbps for replication. you would calculate the 20Mbps change to KBps by dividing the 20 by 8 to get MBps (2.5MBps) and then multiply that by 1024 to get KBps (2560KBps). Edit the agent.cfg and locate the bandwidth=0 location and change that to 2560. The very next time the replication process checks the agent.cfg for that setting the bandwidth will change for that job eventually all jobs conform.

The reason I recommend this method is because you will always use the 20MBps regardless of how many jobs you have running. If you use the second method you will need to calculate how many potential jobs you would be running and then set the OPDUP_BANDWIDTH setting to the 20Mbps divided by the potential amount of jobs and that is what will be used PER job regardless of the number running. If you set OPDUP_BANDWIDTH to 124 KBps and only one job was running then that job would use only 128KBps. With the agent.cfg model you would use all 20Mbps if you had only one job

A more in depth understanding can be seen in the Deduplication administrator's guide http://www.symantec.com/business/support/index?page=content&id=DOC6466 look around page 86.

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Sorry Riaan not Nicoli. Too

Sorry Riaan not Nicoli. Too early and too little coffee. 

I've had very good luck with

I've had very good luck with editing the value in agent.cfg.

But, and this is a big flag, if you have more than one Appliance sending data in the same direction then you may want to either drop the limit sugested by Andrew down a little bit more or watch your SLP's to ensure that only one Appliance is replicating at a time.  The limit is not (and can't be) shared between appliences.  So if you have two appliances set to 2560 and they both are talking at the same time in the same direction then it'll add up to 5120, not 2560...

The other note is that you have to do a Support / Processes / Netbackup stop and then start to re-read the agent.cfg.  And make sure that there are no active jobs going to that Appliance first because the stop command will wait for them to finish and if one is a long running replication...well......

 

 

 

Thanks Everyone and

Thanks Everyone and Andrew for such a good solution. I will implement the same and see the output.