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Question

Multiplexing On Tape

  • 24 August 2023
  • 2 replies
  • 215 views
S
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Userlevel 2
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Hi All,

 

we are actually troubleshooting an perforamnce problem. 

 

There is an Sync Copy top Tape ( LTO 8 ) 

 

2 Mediaagents in a ms csv cluster.

 

When we use combinded streams 1 and multiplexing 1 we only get max 400GB/H troughput the normal jobs have 100GB/h mixed data. 

 

If we increase the multiplexing to 8 and combided to streams 1 the performence grows up over 1500GB/h . 

 

so i have 2 Questions:

 

  1. Is there an limitaion in the stream troughput ? So can 1 Stream only use x GB/h
  2. Wich impact has the multiplexing on tape for the DR Restore process, Does it realy impact the performance so the tape getting in wind/rewind process ? 

2 replies

Emils
Rank
Userlevel 4
Badge +12

Hi @SSchmidt 

Thanks for reaching out, I would recommend reviewing the best practices on multiplexing explained in our documentation.

In saying this, there is no software limitation on a single stream, although a stream performance in influenced by the following factors:

  1. read speed of the source data
  2. The transfer of the data from source to desitation
    1. That would include the network and the medium used to the tape drive (fibre/iscsi etc)
  3. The write speed of the drive/medium

I would use our Performance Analysis Tool to help with identifying the bottleneck

Please ensure to reach out if this answers all your queries or require additional assistance.

S
Rank
Badge +1

I have the same query since. Since we have LTO8 Drivers and when we execute the copies from disk to tapes we see a very good speed of 1500GB/H, but when we want to restore we only reach 70GB/H. We have multiplexing configured with 25. Is there a value that Commvault recommends to work with multiplexing, or is it not recommended to use it?

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