Question

Bandwidth Throttling for a Storage Policy Copy

  • 19 October 2023
  • 1 reply
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Userlevel 2
Badge +12

Hi All,

 

short question regardin the point Bandwidth Throttling for a Storage Policy Copy

 

Setting Network Bandwidth Throttling for a Storage Policy Copy (commvault.com)

 

I want to undersatnd what happend when an auxcopy job starts. 

 

So in normal case without throttelling we reach 500MB/s during auxcopy between 2 DCs over wan. When the auxcopy job starts we see in the firewall the traffic grows up until the wan connection is done. 

 

So when i now throttel the auxcopy to 200MB/s per second we the a lot of peaks in the firewall when the auxcopy job is started. Than it goes down. 

 

My question is: When the auxcopy job starts all streams nad the most getted performance is allocated and that the function with the throttel on sp ract and the speed will be limited ? 

 


1 reply

Userlevel 5
Badge +14

Hello @SSchmidt 

When the job first starts we measure the transfer rate on each stream and how fast it is and then adjust accordingly. You may (as you have) see spikes above the throttle limit as more and more streams get allocated to the job but as the stream allocation levels off it should negotiate to the throttle limit.

Limiting Bandwidth Usage During Backups - https://documentation.commvault.com/v11/expert/7483_limiting_bandwidth_usage_during_backups.htm

l

Relative Bandwidth Throttling

You can limit bandwidth to a percentage of available bandwidth, which is known as relative bandwidth throttling. Relative bandwidth throttling is useful for ensuring acceptable performance when bandwidth available to the client computer is limited.

While sending or receiving, each client in the group monitors the rate at which it can send and receive data. As long as the threshold you enter is below the unthrottled actual rate, clients send or receive as fast as the network will allow. If the actual transmission rate for a client in the group falls below the set threshold, the client begins sending or receiving data at only the throttling percentage you have set. For example, if your threshold is 500Kb/sec, and your percentage is 40%, then transmission is throttled back to 200Kb/sec.

The client imposes this constraint for 30 minutes, and then attempts to operate at full speed again. If it finds that conditions have improved (that is, it can now send or receive data at a rate greater than the threshold you set), it begins sending data at whatever speed the network supports. If it still cannot send or receive data above the threshold rate, it continues to operate at the throttled percentage for another 30 minutes, then checks again, and so on, until the job completes.

 

Thank you,
Collin

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