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Windows server backup has various performance and configuration settings - one of these promises better backup performance but at cost of "performance on the server may be reduced by as much as 200%". My question is, because it isn't clear - is this performance hit just whilst the server is being backed up - or is it all the time?

Thanks.

Manicguitarist
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  • Good question. When setting the backup settings for faster performance, Windows will use a shadow copy to track changes so that subsequent backups will perform faster as a result of just backing up those changes (an incremental backup). It's clear that the backup performance will increase but there's no indication or information related to the performance impact of tracking those changes. - https://msdn.microsoft.com/en-us/library/dd759145.aspx – joeqwerty Mar 02 '16 at 18:11

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After googling a lot - I have found the answer. It seems that the performance hit is the whole time the server is running and not just during backups. This is because all writes to disk are made twice - once to the disk and once to a "copy of changes list" (to simplify). If the server is mainly readonly then that isn't a problem. if it is read/write then disk access is 2x slow.

https://social.microsoft.com/Forums/en-US/607809bc-8495-4d7e-93a3-0f42f5a4dff2/optimize-backup-performance-setting-under-server-manager?forum=whsvailbeta

Manicguitarist
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