Rocky Linux 8 (RHEL 8) Potential for Performance Issue
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In the XCP-ng Documentation, it states there are some performance issues with XFS on kernels prior to 4.20 after a live migration is performed. We decided in our migrations to use Rocky Linux 9 to work around this, but some of our older software only officially supports Rocky Linux 8.10 (kernel 4.18).
The servers will be running databases that live on a secondary drive. Is this still an issue, and if so, would the recommendation be to use EXT4 for both the OS and the data drive?
https://docs.xcp-ng.org/vms/#performance-drop-after-live-migration-for-rhel-8-like-vms
"On some RHEL 8-like systems, running kernels prior to v4.20, and using XFS as default root file system, performance issues have been observed after a live migration under heavy disk activity.XFS seems to have better performances with recent kernels but for older ones we recommend to use another journaled file system like EXT4."
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@plaidypus support, is like a recommendation. It means that the vendor of this software won't help you out if you try to run it on Rocky 9 or later.
The questions I would raise is; Are you actively using support (paying for support) on this software? If so why not just upgrade the software so it supports the current release cycle?
If it's anything other than "we hadn't thought about it" then it's the sunk cost fallacy at which point, stop caring about the "support" and just install it on Rocky 9.
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@DustinB We currently pay for support on this product, and it supposedly supports Rocky Linux 9, but in practice it will not deploy unless we trick it into thinking it is RHEL 9 by swapping out the /etc/redhat-release file. While this workaround did work, our team was not confident in keeping the workaround in place for the automation processes.
Our team wants to get it working with Rocky 9, but upgrading the management software is out of our allowed scope for now (airgapping, InfoSec approvals) and working with their support is slow and our timeline to move these systems is short. Since we know the processes work with Rocky 8, we were instructed to go with that.
With that in mind, I think we are going to set up a new template with ext4 as the filesystem.
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@plaidypus said in Rocky Linux 8 (RHEL
Potential for Performance Issue:@DustinB We currently pay for support on this product, and it supposedly supports Rocky Linux 9,
Then call the software vendor and have them fix their code.... I don't see how this is at all related to XCP-ng or XO, but rather is only this software vendors issue.
Or are you saying that it this software is supported on RHEL, and you're using Rocky linux to avoid purchasing a RHEL license?
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@DustinB The vendor's documentation states official support for RHEL/Rocky/Alma/Oracle Linux 9.0+ systems.
@plaidypus said in Rocky Linux 8 (RHEL
Potential for Performance Issue:Is this still an issue, and if so, would the recommendation be to use EXT4 for both the OS and the data drive?
My apologies, I may have added too much context and information for this. I agree that this is not an issue for XO, but that was also not the original question. If I use Rocky Linux 8 and follow the XCP-ng recommendation in the documentation to use ext4, does this apply to both the root filesystem and also our secondary disk where more of the intensive IO will be?
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@plaidypus You can configure the disk within the guest OS to match whatever formatting you want. I would suspect the performance gains would be included as well, but you'd have to test and verify.