From 4c26efddb13331c3bb27ec2a43625b0158778ca7 Mon Sep 17 00:00:00 2001 From: Teddy Astie Date: Wed, 26 Nov 2025 11:01:13 +0100 Subject: [PATCH 1/4] requirements: Modernize requirements XCP-ng 8.3 doesn't support "paravirtualized mode" anymore, it doesn't make sense to keep informations related to it. e.g hardware virtualization is now mandatory (not only for Windows) and XCP-ng will refuse to install without it. Recommend the use of a IOMMU, while not always required, it's fair to recommended it, especially since some machines could require it (e.g to use more than 256 cores). Increase memory recommendation, it's not advisable to use XCP-ng with 4 GB of memory. Fix theorical CPU limit with currently used Xen limit. Signed-off-by: Teddy Astie --- docs/installation/requirements.md | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/docs/installation/requirements.md b/docs/installation/requirements.md index 302ee286..23ed6314 100644 --- a/docs/installation/requirements.md +++ b/docs/installation/requirements.md @@ -25,20 +25,17 @@ The system requirements for XCP-ng are: ### CPUs - One or more 64-bit x86 CPUs, minimum 1.5 GHz; 2 GHz or faster multicore CPUs are recommended. -- To run Windows VMs or recent Linux versions, an Intel VT or AMD-V 64-bit x86-based system with one or more CPUs is required. - -> **Note**: For Windows VMs or newer Linux distributions, enable hardware virtualization in the BIOS. It may be disabled by default—consult your BIOS documentation for guidance. - -- For VMs running supported paravirtualized Linux, a standard 64-bit x86-based system with one or more CPUs is required. +- Hardware virtualization must be enabled (Intel VT-x or AMD-V), it may be disabled by default—consult your BIOS documentation for guidance. +- Enabling IOMMU (Intel VT-d or AMD-Vi) is recommended ### Memory -- Minimum 2 GB, recommended 4 GB or more. +- Minimum 2 GB, recommended 8 GB or more. - A fixed amount of RAM is allocated to the control domain (dom0). Optimal allocation depends on your workload. ### Disk Space -- Local storage (PATA, SATA, SCSI) with a minimum of 46 GB, recommended 70 GB or more. +- Local storage (PATA, SATA, SCSI, NVMe) with a minimum of 46 GB, recommended 70 GB or more. - SAN access via HBA (not software) when installing with multipath boot from SAN. For more details, refer to the [Hardware Compatibility List (HCL)](../../installation/hardware). @@ -98,7 +95,7 @@ The maximum number of supported logical processors may vary depending on the CPU XCP-ng 8.2 is EOL. This 8.2-specific information is retained solely to assist with the transition from 8.2 to a supported release. ::: -- Up to 960 logical processors, depending on CPU support (theoretical, untested: 1024). +- Up to 960 logical processors, depending on CPU support (theoretical, untested: 2048). #### XCP-ng 8.2 LTS @@ -183,7 +180,7 @@ A resource pool is a collection of one or more servers (up to 64), which can be ### Hardware Requirements -- All servers must have compatible CPUs (same vendor — Intel or AMD). To run HVM VMs, CPUs must support virtualization. +- All servers must have compatible CPUs (same vendor — Intel or AMD). ### Additional Pool Requirements From bf30cceb3d67b823c8fede74c8d24cefcf23a12d Mon Sep 17 00:00:00 2001 From: Teddy Astie Date: Wed, 26 Nov 2025 11:02:52 +0100 Subject: [PATCH 2/4] requirements: Reformat maximum disk size 2040 GiB is quite confusing and incorrect, and is actually 2 TiB. Signed-off-by: Teddy Astie --- docs/installation/requirements.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/docs/installation/requirements.md b/docs/installation/requirements.md index 23ed6314..a656289a 100644 --- a/docs/installation/requirements.md +++ b/docs/installation/requirements.md @@ -161,9 +161,9 @@ XCP-ng 8.2 is EOL. This 8.2-specific information is retained solely to assist wi - **Virtual Disk Images per VM (including CD-ROMs)**: Up to **241**. This is also influenced by the limits of your guest OS; refer to its documentation to ensure compatibility. - **Virtual CD-ROM drives per VM**: **1**. - **Maximum Virtual Disk Size**: - - **2,040 GiB** using storage drivers with the VHD format (`Local EXT`, `Local LVM`, `NFS`, `LVM over iSCSI`, `XOSTOR`, etc.). + - **2 TiB** using storage drivers with the VHD format (`Local EXT`, `Local LVM`, `NFS`, `LVM over iSCSI`, `XOSTOR`, etc.). - Nearly unlimited when using the `raw` storage driver or disk pass-through to the VM (note: snapshots and live migration are not supported in these cases). - - New storage drivers are under active development to overcome the **2,040 GiB** VHD limit while retaining features like snapshots and live migration. + - New storage drivers are under active development to overcome the **2 TiB** VHD limit while retaining features like snapshots and live migration. ### Networking From 35dc337026632badb96368158d8fcc1a645a3e1d Mon Sep 17 00:00:00 2001 From: Teddy Astie Date: Wed, 26 Nov 2025 11:06:29 +0100 Subject: [PATCH 3/4] requirements: Improve vCPU limit Tested limit is actually the maximum limit. Xen don't allow further than that as of today. Say "guest may limit" as in practice, the guest will likely boot but with less vCPUs usable. Warn about potential performance implications of VMs with a lot of vCPUs and Windows guests with more than 64 vCPU. Signed-off-by: Teddy Astie --- docs/installation/requirements.md | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/docs/installation/requirements.md b/docs/installation/requirements.md index a656289a..68b38d42 100644 --- a/docs/installation/requirements.md +++ b/docs/installation/requirements.md @@ -119,9 +119,14 @@ Below are the supported limits for virtual machines on XCP-ng. - **Virtual CPUs (vCPUs) per VM**: - For untrusted VMs, the security-supported limit is **32 vCPUs**. - - For trusted VMs, the tested limits are **128 vCPUs** in BIOS mode and **96 vCPUs** in UEFI mode. Developments are planned to increase these limits. + - For trusted VMs, the maximum limits are **128 vCPUs** in BIOS mode and **96 vCPUs** in UEFI mode. Developments are planned to increase these limits. -Guest OS support is also an important factor to consider. +Guest OS may limit the amount of usable vCPUs. + +:::warning +VMs with more than 32 vCPU may cause major system-wide performance degradation under very specific circumstances. Use with caution. +Windows VMs with more than 64 vCPUs are not supported. +::: #### XCP-ng 8.2 LTS From 738c3ffeb55a0267ee849753b1120f8b3c522a4e Mon Sep 17 00:00:00 2001 From: Teddy Astie Date: Wed, 26 Nov 2025 11:10:23 +0100 Subject: [PATCH 4/4] requirements: Clarify NIC limit Current wording is quite confusing and suggest that operating system has a inherent NIC limit which is probably not the case (or at least, not at this limit). The reality is more likely that lack of netif support means that VM relies on emulated devices, which has some limitations (i.e we may not expose all NICs as a emulated device). Signed-off-by: Teddy Astie --- docs/installation/requirements.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/installation/requirements.md b/docs/installation/requirements.md index 68b38d42..b2c20fbb 100644 --- a/docs/installation/requirements.md +++ b/docs/installation/requirements.md @@ -173,7 +173,7 @@ XCP-ng 8.2 is EOL. This 8.2-specific information is retained solely to assist wi ### Networking - **Virtual Network Interface Controllers (NICs) per VM**: Up to **7**. - Note: Some guest operating systems may have stricter limits, or you may need to install XCP-ng Guest Tools to reach this maximum. + Use of paravirtualized devices is recommended, support depends on guest operating system and whether or not XCP-ng Guest Tools are installed. ### Other