仮想環境上の RHEL5 系へディスクを動的追加

OpenStack MLで教えてもらったのでメモ。

この手順で仮想マシン上のRHEL5にディスクをホットプラグできる。

** RHEL6系は標準カーネルで対応しているのでこの手順は必要無し。


RHEL6系はホストマシンから

host# virsh attach-disk rhel6-vm /disk-file.img vdb

として仮想ディスクを追加すると、
guest# udevadm monitor

KERNEL[1347495382.970520] remove   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:0b (acpi)
KERNEL[1347495382.970594] add      /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:22 (acpi)
UDEV  [1347495382.970629] remove   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:0b (acpi)
UDEV  [1347495382.990487] add      /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:22 (acpi)
KERNEL[1347495383.039877] add      /devices/pci0000:00/0000:00:09.0 (pci)
UDEV  [1347495383.048273] add      /devices/pci0000:00/0000:00:09.0 (pci)
KERNEL[1347495383.054381] add      /devices/pci0000:00/0000:00:09.0/virtio5 (virtio)
UDEV  [1347495383.073997] add      /devices/pci0000:00/0000:00:09.0/virtio5 (virtio)
KERNEL[1347495383.074533] add      /devices/virtual/bdi/252:16 (bdi)
UDEV  [1347495383.075088] add      /devices/virtual/bdi/252:16 (bdi)
KERNEL[1347495383.077906] add      /devices/pci0000:00/0000:00:09.0/virtio5/block/vdb (block)
UDEV  [1347495383.104685] add      /devices/pci0000:00/0000:00:09.0/virtio5/block/vdb (block)

このようにカーネル(udev)がイベントを取得でき、動的にデバイスの接続が可能。

同様に削除も可能、
host# virsh detach-disk rhel6-vm vdb
guest# udevadm monitor

KERNEL[1347495416.974120] remove   /devices/virtual/bdi/252:16 (bdi)
UDEV  [1347495416.975045] remove   /devices/virtual/bdi/252:16 (bdi)
KERNEL[1347495416.975760] remove   /devices/pci0000:00/0000:00:09.0/virtio5/block/vdb (block)
UDEV  [1347495416.977335] remove   /devices/pci0000:00/0000:00:09.0/virtio5/block/vdb (block)
KERNEL[1347495416.979012] remove   /devices/pci0000:00/0000:00:09.0/virtio5 (virtio)
UDEV  [1347495416.979855] remove   /devices/pci0000:00/0000:00:09.0/virtio5 (virtio)
KERNEL[1347495416.982315] remove   /devices/pci0000:00/0000:00:09.0 (pci)
UDEV  [1347495416.983299] remove   /devices/pci0000:00/0000:00:09.0 (pci)
KERNEL[1347495416.984000] remove   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:22 (acpi)
UDEV  [1347495416.985072] remove   /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:22 (acpi)

しかしRHEL5系の場合、
host# virsh attach-disk rhel5-vm /disk-file.img vdb

標準でイベントを拾うことができない。
guest# udevmonitor

空

これはacpiphpモジュールをロードさせることでホットプラグが可能になる。

以下のファイルを作成して、起動時のロードされるように設定しておく。
guest# vim /etc/sysconfig/modules/acpiphp.modules

#!/bin/bash
modprobe acpiphp

guest# chmod +x /etc/sysconfig/modules/acpiphp.modules

再起動 or modprode acpiphp

guest# lsmod |grep acpiphp

acpiphp                58841  0

host# virsh attach-disk rhel5-vm /disk-file1.img vdb
host# virsh attach-disk rhel5-vm /disk-file2.img vdc
host# virsh attach-disk rhel5-vm /disk-file3.img vdd

UEVENT[1347501300.539658] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S8
UDEV  [1347501300.539658] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S8
UEVENT[1347501300.571892] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S8
UEVENT[1347501300.590224] add@/devices/pci0000:00/0000:00:08.0
UEVENT[1347501300.607140] add@/devices/virtio-pci/virtio3
UEVENT[1347501300.625218] add@/block/vdb
UEVENT[1347501300.633221] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S7
UEVENT[1347501300.653192] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S7
UEVENT[1347501300.683148] add@/devices/pci0000:00/0000:00:07.0
UEVENT[1347501300.708434] add@/devices/virtio-pci/virtio4
UEVENT[1347501300.719171] add@/block/vdc
UEVENT[1347501300.719818] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S6
UEVENT[1347501300.720584] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S6
UEVENT[1347501300.730112] add@/devices/pci0000:00/0000:00:06.0
UEVENT[1347501300.730791] add@/devices/virtio-pci/virtio5
UEVENT[1347501300.731774] add@/block/vdd
UDEV  [1347501302.251070] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S7
UDEV  [1347501302.691188] remove@/firmware/acpi/namespace/ACPI/_SB/PCI0/S6
UDEV  [1347501304.566026] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S8
UDEV  [1347501304.619257] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S7
UDEV  [1347501304.868756] add@/firmware/acpi/namespace/ACPI/_SB/PCI0/S6
UDEV  [1347501305.519140] add@/devices/pci0000:00/0000:00:08.0
UDEV  [1347501307.512506] add@/devices/virtio-pci/virtio3
UDEV  [1347501309.464859] add@/block/vdb
UDEV  [1347501311.182177] add@/devices/pci0000:00/0000:00:07.0
UDEV  [1347501312.350176] add@/devices/virtio-pci/virtio4
UDEV  [1347501312.976733] add@/block/vdc
UDEV  [1347501314.987497] add@/devices/pci0000:00/0000:00:06.0
UDEV  [1347501316.405359] add@/devices/virtio-pci/virtio5
UDEV  [1347501317.083238] add@/block/vdd

無事認識できました。

参考：http://www.linux-kvm.org/page/Hotadd_pci_devices