Availability for the Always-On Enterprise
DavidReimers
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Full Name: David Reimers
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Re: REFS or NTFS?

Post by DavidReimers » Jan 07, 2019 11:53 pm 1 person likes this post

To accelerate the restore process, Veeam Backup & Replication creates a map of data blocks in backup files. It uses the created map to read data blocks of VM disks from backup files sequentially, as they reside on disk. Veeam Backup & Replication writes data blocks to target in the order in which they come from the target Veeam Data Mover, restoring several VM disks in parallel.
Which explains why the problem doesn't affect Veeam, but affects other applications reading the same data. In my customer's case, he's using Arcserve to backup the VBK files - so he's then getting the problem of poor random read performance.

kubimike
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Re: REFS or NTFS?

Post by kubimike » Jan 08, 2019 3:20 pm

enoch wrote:
Dec 31, 2018 1:14 pm
Thanks looking forward for what the teams have to say.

If anyone else have any recommended recovery way to get the REFS drive from RAW to "normal" state i'll be very happy :D
I could give you the beta driver to try.

Frenchyaz
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Re: REFS or NTFS?

Post by Frenchyaz » Jan 09, 2019 3:02 pm 1 person likes this post

If you want to use deduplication either with ReFS or NTFS, you have to limit your volume size to 64TB.
So far we are using successfully ReFS with dedupe on Windows 2019 and no issues whatsoever.

PTide
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Re: REFS or NTFS?

Post by PTide » Jan 09, 2019 5:14 pm 1 person likes this post

If you want to use deduplication either with ReFS or NTFS, you have to limit your volume size to 64TB
...and also you should keep an eye on the size of your backup files:
Deduplication is not supported on:

System or boot volumes
<...>
Files approaching or larger than 1 TB in size.
<...>

Frenchyaz
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Re: REFS or NTFS?

Post by Frenchyaz » Jan 14, 2019 4:02 pm

We have oversized backup files (7.4TB) deduped okay on ReFS (3.42TB on disk), doesn't seem to be an issue however the time to dedup files >1TB may be slower than files <1TB and the dedup ration may be lower.

nmdange
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Re: REFS or NTFS?

Post by nmdange » Jan 14, 2019 5:30 pm 1 person likes this post

If the file is over 1TB, only the first 1TB of data within the file gets deduplicated.

DonZoomik
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Re: REFS or NTFS?

Post by DonZoomik » Jan 14, 2019 7:47 pm

This is incorrect. First 4TB get deduplicated since WS2016 (unlimited in 2012 and 2012R2).
The limit may have been raised in WS2019 (ReFS only?) if Frenchyaz'es numbers are correct. Please check properties for backup files, is any of them larger than 4TB? In that case size on disk should be smaller than (Size minus 4TB).
Haven't had time to test yet myself.

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