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Recommended concurrency for LTO 5 drive?

Hi folks,

 

Whats the recommended concurrency for LTO 5 drives? Does it depend on the data transfer rate?

 

Thanks!

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Admiral
Admiral

Set it to the number of backup objects you will be backing up in the job. Each line in the 'Backup Object Summary' counts as one stream, so make concurrency equal to that.

In my environment, my drive settings are this:
- Concurrency: 20
- Detect dirty drive
- SCSI Reserver/Release (drive)
- Block Size: 512 KB
- Segment Size: 10000 MB
- Disk Agent Buffers: 32
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I have about 60 objects in 2 backup specifications, about 30-35 in a few others and one larger one. I wouldnt set the concurrency according to the number of objects. At a setting of 20, are you satisfied with the performance?

What's the recommended setting for LTO5? HP have always recommended a concurrency of 8 for LTO4 drives.
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Hi, there is no general recommendation about the concurrency, except do not use the default values. The setting depends on your environment. I recommend to use a concurrency until the drive becomes saturated. In some environments you might need 10 or more in other environments it might require only 8 or less. So make performance tests in your environment (use omnispeed from data-protector.org) and adjust the backup specification after you have analysed the results from your performance tests. Best regards Daniel
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@eMeS wrote:
What's the recommended setting for LTO5? HP have always recommended a concurrency of 8 for LTO4 drives.

There can't be a straight recommendation. The concurrency is a tradeoff, you buy faster backups at the price of painfully slow restores. Finding a proper middle ground is hard. My recommendation: Use as many parallel objects as necessary to keep the drive streaming, but refrain from exceeding that number too much. Streaming is essential to keep backups perform well and not break drive and media early by mechanical stress and abrasion. But beyond that, additional streams are mostly thinning out the bandwidth available for every single one of them, and that's mostly the bandwidth you'll see on restore of said object. So choose wisely. Or use D2D2T with single-object streams to lots of virtual tapes, followed by a non-multiplexing copy to real tape.

 

HTH,

Andre.

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Sorry guys I should have replied earlier, but thank you for taking the time to advise and clearing my misconception.
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