Running ReFS + deduplication + fastclone results in really slow fastclone unless you modify your optimization job to run after the synthetic full is created.
jorgedlcruz wrote: ↑
Mar 13, 2019 1:50 pm
But that will be expected I will say isn't? To obtain the best possible performance, at a logical level really, you will need to use the usual ReFS for your synthetic, might be weekly or so, and then once you know your synthetic file is created, that is the file you want to apply dedupe.
So, look at your Windows Deduplication schedule and make sure you are not doing dedupe on the files of the open chain which will be used to create the synthetic, as if you do the server will need to dedupe all that files before do the ReFS, which will end in that long time to do the fast-clone.
We have multiple repositories, most of them with ReFS + deduplication. Synthetic Fulls take days to complete. Space savings are great, savings around 100-150% (Capacity 40TB, Used Space 79,4TB; Capacity 64TB, Used Space 165TB)
The ones that are not deduplicated runs much faster and space savings are around 40%
So my recommendation is to stick use ReFS without enabling windows deduplication if you want your synthetic fulls to complete. If you have a schedule where you only make backups on weekdays, you could probably enable deduplication and run the synthetic full on fridays, and hopefully it will be done until monday