Commvault Deduplication activity while Windows Deduplication is running

Question

Hello Commvault Community,

I have questions for you about the operation of the Commvault Deduplication mechanism on the server (Windows Server 2012) where the Windows Deduplication mechanism is also working.

I realize that it is not recommended to use both mechanisms at the same time.

My guess is that if files are deduplicated by Windows Deduplication then when backed up by Commvault they are deduplicated again by Commvault's Deduplication mechanism. If not, please explain to me what it looks like.

What if the Client wants to use the Restore jobs to recover such deduplicated (possibly double files)? Are they recoverable or if there are problems and you find that the files are unrecoverable.

Another question, what in the case of archiving on data deduplicated by Windows Deduplication, will they be able to be re-duplicated and later archived by Commvault? Can only new files that are not deduplicated by Windows Deduplication be backed up? From the Commvault archiving documentation I found information that deduplicated files by Microsoft cannot be archived, but can they somehow be reduplicated and archived by Commvault?

Windows File System Archiving
https://documentation.commvault.com/commvault/v11/article?p=25799.htm

If I have described something vaguely, please let me know.

Please help answer these questions.

Thank you for your help.
Regards
Kamil

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Best answer by DR92 30 June 2021, 21:06

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DR92 · Accepted Answer

Hey@KamilSo there are several questions in your post  , let me start off by trying to answer a few of them.I realize that it is not recommended to use both mechanisms at the same time.Not really, there is no such recommendation, was this just intuition or did you come across any article that led you to believe that both can’t be used at the same time ?My guess is that if files are deduplicated by Windows Deduplication then when backed up by Commvault they are deduplicated again by Commvault's Deduplication mechanism. If not, please explain to me what it looks like.Correct, Windows deduplication would work on the volumes it is configured for on the client, deduplication configured for a storage policy would not act on the source volumes but rather on the Media Agent’s storage solution, so, let’s say you’re using a disk on the Media Agent side, the data written would be a lot lower (based on the deduplication ratio)if you’re using Commvault’s deduplication i.e. deduplicated storage policy.What if the Client wants to use the Restore jobs to recover such deduplicated (possibly double files)? Are they recoverable or if there are problems and you find that the files are unrecoverable.There shouldn’t be any issues during recovery of such files.UPDATE (07/01)Another question, what in the case of archiving on data deduplicated by Windows Deduplication, will they be able to be re-duplicated and later archived by Commvault? Can only new files that are not deduplicated by Windows Deduplication be backed up? From the Commvault archiving documentation I found information that deduplicated files by Microsoft cannot be archived, but can they somehow be reduplicated and archived by Commvault?Windows File System Archivinghttps://documentation.commvault.com/commvault/v11/article?p=25799.htmCorrect, Windows deduplicated files cannot be archived however it is possible to reduplicate the files and then immediately archive them by using scripts, we can help with that.Let me know if I missed anything or if you’re looking for more information.ThanksDhiwakar

DR92 · Answer

@Kamil, I’ve updated my reply.

Commvault Deduplication activity while Windows Deduplication is running

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