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Dash Copy from DDB Disk Library to HPE StoreOnce

  • 1 June 2022
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Userlevel 2
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Hello to all,

In case of local Disk Library with Commvault DDB enabled, If create a replication/secondary job to a HPE StoreOnce as target, these jobs are going to transfer only the changed data blocks ? Like Dash copy? Or the entire physically copying data for every job?

The goal is to reduce the data / traffic for replicated jobs.

Please for your help 😀
 

Thank you in advance,
Nikos

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Best answer by Laurent 1 June 2022, 17:01

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Userlevel 6
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Hi @Nikos.Kyrm 

Well, depending on how you setup the target (HPE StoreOnce) and your copy, it can benefit from the use of deduplication (dash) or not at all.

If you want to reduce traffice for replicated jobs, then you should probably use Commvault deduplication with your StoreOnce (I hope this device does not perform deduplication) and DASH Copy.

Regards,

Laurent.

Userlevel 2
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Dear @Laurent ,

Thanks for your reply!

Basically, from what I know the duplication in StoreOnce is natively enabled, so the Commvault DDB is going to be disabled for StoreOnce MA.

So, that’s why Im asking, if there is any way for the replication jobs (from DDB local Disk Library) to the StoreOnce (deduplication from StoreOnce) to transfer only the changed data blocks in order to save some data / traffic.

Thank you in advance,
Nikos

Userlevel 6
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Well, then you have yourself the answer 😉

I have never worked with this device, but I already have worked on other devices that offered deduplication features.

But, on some, deduplication is performed seamlessly on the fly (achieving less dedup ratio but faster data access) as with PureStorage Flashblades for example, while for other it’s almost on the fly but with post-operation compression (like daily, or weekly...) as on Dell/EMC Datadomain for another example. Their purpose is to achieve better post-comp/operation deduplication ratios.

On the first case, it’s no problem but you may use more storage space, while on the second, it would “cost” you performance, especially while reading data out of this storage.

There are also devices where you can disable the deduplication.

 

If you let Commvault deduplication active on primary storage, and do not activate the Commvault deduplication on the new storage library, then data will be hydrated for your copy, and this is probably the scenario that would generate the more trafic between the two. 

 

Userlevel 2
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Dear @Laurent I see!

So, in case to have DASH copies (replication jobs which transfers only the changed data blocks and achieve less traffic) the only way is to disable the reduplication from the backup appliance (if supported) and use it as a “dummy” Storage Library with DDB enabled to the attached MA.

Is that right ?

Many thanks,
Nikos

Userlevel 6
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I would say ‘right’, on paper, yes 😉

I always ask my storage vendors (that I would use to store my backups) for a dummy storage, without any intelligence, because I prefer my backups to rely on one tool (Commvault) than on several layers that would be difficult to manage, especially when troubles come and you have to troubleshoot 😊

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