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Re: Server 2025 - high CPU and RAM
What is the trigger to this issue? iSCSI repository? or very huge repository?
Marco
Marco
Ciao,
Marco
Marco
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- Chief Product Officer
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Re: Server 2025 - high CPU and RAM
Neither. The working theory is that some improvements in metadata handling logic in Server 2025 made ReFS caching so much metadata that it's causing system to go out of memory. ReFS does have a cache throttle, but certain code path is apparently ignoring it, thus the issue.
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Re: Server 2025 - high CPU and RAM
So far I have installed two or three (little) Veeam Backup Server with Dell hardware, PowerEdge T360, and I din't incur in the issue
Finger crossed
Marco
Finger crossed
Marco
Ciao,
Marco
Marco
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Re: Server 2025 - high CPU and RAM
Hi,
is there any update or fix regarding this issue? We are also experiencing this.
is there any update or fix regarding this issue? We are also experiencing this.
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Re: Server 2025 - high CPU and RAM
See my post a few hours ago 

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Re: Server 2025 - high CPU and RAM
Any update on this?
Having the same issues, VM locking on backup, typically 4/5th backup. Have to reset it via ESXi.
CPU at 100% when looking at it on ESXi.
Windows 11 24H2 26100.3775
REFS Volume Version : 3.14
Having the same issues, VM locking on backup, typically 4/5th backup. Have to reset it via ESXi.
CPU at 100% when looking at it on ESXi.
Windows 11 24H2 26100.3775
REFS Volume Version : 3.14
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Re: Server 2025 - high CPU and RAM
Updates will be posted as soon as we have them. Why would we start keeping them secret all of a sudden? 

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Re: Server 2025 - high CPU and RAM
This (I'll call it a workaround until the official hotfix comes out) worked for me on a Server 2025 setup that was experiencing the same freezing issues posted by others as well:
post536519.html#p536519
Wally
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Re: Server 2025 - high CPU and RAM
Thanks, Wally, will give this a go. Anyone else really not like REFS? I've only had issues with it, it's been out for a while now, but still feels like a beta product.
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Re: Server 2025 - high CPU and RAM
@SpikeAUS At the current rate of issues i would rather host a Linux virtual machine with XFS on the Veeam Server (under Hyper-V) than use ReFS directly...
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Re: Server 2025 - high CPU and RAM
Thanks Wally.wallstrum wrote: ↑Apr 16, 2025 3:09 pm This (I'll call it a workaround until the official hotfix comes out) worked for me on a Server 2025 setup that was experiencing the same freezing issues posted by others as well:
post536519.html#p536519
Wally
We are using Server 2019. Will this also work?
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Re: Server 2025 - high CPU and RAM
Server 2019 should not be affected by the same issue that we're talking about here (only Server 2025 & Windows 11)
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Re: Server 2025 - high CPU and RAM
Hi all!
Mid March 2025 we had upgraded our veeam server to Windows Server 25, since the old 2019 Server was not able to read the ReFS filesystems from backed up Server 2022 machines.
Afterwards we noticed also these freezes related to ReFS.
Does anybody know, if these issues had been fixed in this update I installed recently?
"2025-04 Kumulatives Update für Microsoft server operating system version 24H2 für x64-basierte Systeme (KB5055523)"
Thanks
jokoenen
Mid March 2025 we had upgraded our veeam server to Windows Server 25, since the old 2019 Server was not able to read the ReFS filesystems from backed up Server 2022 machines.
Afterwards we noticed also these freezes related to ReFS.
Does anybody know, if these issues had been fixed in this update I installed recently?
"2025-04 Kumulatives Update für Microsoft server operating system version 24H2 für x64-basierte Systeme (KB5055523)"
Thanks
jokoenen
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Re: Server 2025 - high CPU and RAM
Hi, Server 2019 being unable to read Server 2022 ReFS volumes is not an issue but rather the expected behavior: ReFS driver in Server 2019 simply does not have any knowledge of newer ReFS versions. Thanks
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Re: Server 2025 - high CPU and RAM
Hi everyone!
Looking bachwards, the incompatibility of the different ReFS versions is a feature, not an issue. What was surprising, that filesystems of backups of 2022 ReFS done with den 2019 server have not been readable with the 2025 server. So the requrements of ReFS are very strict. So everything has to fit: the creator of the filesystem, the backup maker and the backup reader. Luckily NTFS seeams to be compatible between different OS version.
LG
Jokoenen
Looking bachwards, the incompatibility of the different ReFS versions is a feature, not an issue. What was surprising, that filesystems of backups of 2022 ReFS done with den 2019 server have not been readable with the 2025 server. So the requrements of ReFS are very strict. So everything has to fit: the creator of the filesystem, the backup maker and the backup reader. Luckily NTFS seeams to be compatible between different OS version.
LG
Jokoenen
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Re: Server 2025 - high CPU and RAM
so what is the actual recommendation for new deployments right now? go with 2022 for ReFS repositories and all other infrastructure components?
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Re: Server 2025 - high CPU and RAM
Correct.
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