From a901390617a4ba8f6d69a2a105fb012829af2f0a Mon Sep 17 00:00:00 2001 From: Roger Heslop Date: Fri, 15 May 2026 15:47:31 -0500 Subject: [PATCH 1/2] Recommended changes for DOCPLAN#185 --- modules/hcp-virt-map-storage.adoc | 8 ++++---- modules/virt-about-storage-volumes-for-vm-disks.adoc | 5 +++++ modules/virt-configuring-vm-disk-sharing.adoc | 5 +++-- modules/virt-customizing-storage-profile.adoc | 5 +++++ modules/virt-enabling-persistent-efi.adoc | 2 +- modules/virt-storage-wizard-fields-web.adoc | 2 +- 6 files changed, 19 insertions(+), 8 deletions(-) diff --git a/modules/hcp-virt-map-storage.adoc b/modules/hcp-virt-map-storage.adoc index d5a13962fd01..bfcdee2c2520 100644 --- a/modules/hcp-virt-map-storage.adoc +++ b/modules/hcp-virt-map-storage.adoc @@ -43,10 +43,10 @@ The following table shows how volume and access mode capabilities map to KubeVir |=== | Infrastructure CSI capability | Hosted cluster CSI capability | VM live migration support | Notes -| RWX: `Block` or `Filesystem` -| `ReadWriteOnce` (RWO) `Block` or `Filesystem` RWX `Block` only +| RWX: `Block` +| `ReadWriteOnce` (RWO): `Block` or `Filesystem`, RWX: `Block` only | Supported -| Use `Block` mode because `Filesystem` volume mode results in degraded hosted `Block` mode performance. RWX `Block` volume mode is supported only when the hosted cluster is {product-title} 4.16 or later. +| You must use `Block` volume mode with RWX access mode. `Filesystem` volume mode is not supported with RWX for virtual machine storage. RWX `Block` volume mode is supported only when the hosted cluster is {product-title} 4.16 or later. | RWO `Block` storage | RWO `Block` storage or `Filesystem` @@ -58,4 +58,4 @@ The following table shows how volume and access mode capabilities map to KubeVir | Not supported | Lack of live migration support affects the ability to update the underlying infrastructure cluster that hosts the KubeVirt VMs. Use of the infrastructure `Filesystem` volume mode results in degraded hosted `Block` mode performance. -|=== \ No newline at end of file +|=== diff --git a/modules/virt-about-storage-volumes-for-vm-disks.adoc b/modules/virt-about-storage-volumes-for-vm-disks.adoc index 206a769cb9b1..fdb8cca720ef 100644 --- a/modules/virt-about-storage-volumes-for-vm-disks.adoc +++ b/modules/virt-about-storage-volumes-for-vm-disks.adoc @@ -19,6 +19,11 @@ For best results, use the `ReadWriteMany` (RWX) access mode and the `Block` volu * `ReadWriteMany` (RWX) access mode is required for live migration. * The `Block` volume mode performs significantly better than the `Filesystem` volume mode. This is because the `Filesystem` volume mode uses more storage layers, including a file system layer and a disk image file. These layers are not necessary for VM disk storage. +[IMPORTANT] +==== +You must use `Block` volume mode with `ReadWriteMany` (RWX) access mode for virtual machine disks. The `Filesystem` volume mode is not supported with RWX access mode for VM storage. +==== + ifndef::openshift-rosa,openshift-dedicated,openshift-rosa-hcp[] + For example, if you use {rh-storage-first}, Ceph RBD volumes are preferable to CephFS volumes. diff --git a/modules/virt-configuring-vm-disk-sharing.adoc b/modules/virt-configuring-vm-disk-sharing.adoc index 29078b77a14a..62d2eb5c5e24 100644 --- a/modules/virt-configuring-vm-disk-sharing.adoc +++ b/modules/virt-configuring-vm-disk-sharing.adoc @@ -27,9 +27,10 @@ If the VMs that are sharing disks are running on the same node, `ReadWriteOnce` + [NOTE] ==== -Not all filesystem and format combinations support RWX mode. For example, XFS format does not support RWX mode. When multiple VMs write to an XFS-formatted volume, data corruption occurs and only the writing VM can access the data. -==== +The persistent volume claim (PVC) must use `Block` volume mode with `ReadWriteMany` (RWX) access mode. The `Filesystem` volume mode is not supported with RWX for virtual machine disks. +Not all guest filesystems support concurrent access. For example, XFS does not support `RWX` mode and can experience data corruption when shared between VMs. +==== * The storage provider must support the required Container Storage Interface (CSI) driver. diff --git a/modules/virt-customizing-storage-profile.adoc b/modules/virt-customizing-storage-profile.adoc index 77b44d0dad89..65d8706049d6 100644 --- a/modules/virt-customizing-storage-profile.adoc +++ b/modules/virt-customizing-storage-profile.adoc @@ -56,3 +56,8 @@ status: + * `spec.claimPropertySets.accessModes` defines how the volume can be mounted. For example, `ReadWriteOnce` * `spec.claimPropertySets.accessModes.volumeMode` defines whether the volume uses a file system or raw block storage. For example, `volumeMode`. ++ +[IMPORTANT] +==== +The `Filesystem` volume mode is not supported with `RWX` access mode for VM storage. Use `RWX` access mode only when `volumeMode` is `Block`. +==== diff --git a/modules/virt-enabling-persistent-efi.adoc b/modules/virt-enabling-persistent-efi.adoc index 83541785c7cc..c6892945ace9 100644 --- a/modules/virt-enabling-persistent-efi.adoc +++ b/modules/virt-enabling-persistent-efi.adoc @@ -21,7 +21,7 @@ ifdef::openshift-dedicated[] * You must have a storage class that supports filesystem (`FS`) volume mode and the access mode required for persistent EFI state. endif::openshift-dedicated[] ifndef::openshift-dedicated[] -* You must have a storage class that supports RWX access mode and FS volume mode. +* You must have a storage class that supports RWX access mode and Block volume mode. endif::openshift-dedicated[] * You have installed the {oc-first}. diff --git a/modules/virt-storage-wizard-fields-web.adoc b/modules/virt-storage-wizard-fields-web.adoc index bb9338152c10..23cd32d13225 100644 --- a/modules/virt-storage-wizard-fields-web.adoc +++ b/modules/virt-storage-wizard-fields-web.adoc @@ -73,7 +73,7 @@ ifndef::openshift-dedicated[] |ReadWriteOnce (RWO) |Volume can be mounted as read/write by a single node. |ReadWriteMany (RWX) -|Volume can be mounted as read/write by many nodes at one time. +|Volume can be mounted as read/write by many nodes at one time. You can only use RWX access mode with the `Block` volume mode. [NOTE] ==== This mode is required for live migration. From dcf4fe6a927ed0b72bca3c96805b0523287fce32 Mon Sep 17 00:00:00 2001 From: Roger Heslop Date: Wed, 20 May 2026 15:57:12 -0500 Subject: [PATCH 2/2] Revert modules/hcp-virt-map-storage.adoc --- modules/hcp-virt-map-storage.adoc | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/modules/hcp-virt-map-storage.adoc b/modules/hcp-virt-map-storage.adoc index bfcdee2c2520..d5a13962fd01 100644 --- a/modules/hcp-virt-map-storage.adoc +++ b/modules/hcp-virt-map-storage.adoc @@ -43,10 +43,10 @@ The following table shows how volume and access mode capabilities map to KubeVir |=== | Infrastructure CSI capability | Hosted cluster CSI capability | VM live migration support | Notes -| RWX: `Block` -| `ReadWriteOnce` (RWO): `Block` or `Filesystem`, RWX: `Block` only +| RWX: `Block` or `Filesystem` +| `ReadWriteOnce` (RWO) `Block` or `Filesystem` RWX `Block` only | Supported -| You must use `Block` volume mode with RWX access mode. `Filesystem` volume mode is not supported with RWX for virtual machine storage. RWX `Block` volume mode is supported only when the hosted cluster is {product-title} 4.16 or later. +| Use `Block` mode because `Filesystem` volume mode results in degraded hosted `Block` mode performance. RWX `Block` volume mode is supported only when the hosted cluster is {product-title} 4.16 or later. | RWO `Block` storage | RWO `Block` storage or `Filesystem` @@ -58,4 +58,4 @@ The following table shows how volume and access mode capabilities map to KubeVir | Not supported | Lack of live migration support affects the ability to update the underlying infrastructure cluster that hosts the KubeVirt VMs. Use of the infrastructure `Filesystem` volume mode results in degraded hosted `Block` mode performance. -|=== +|=== \ No newline at end of file