A.2.39 Usage in Oracle VM Environment

When managing disks used in Oracle VM environment by GDS, there are the following methods:

How to use GDS in a control domain or an I/O root domain and manage disks used in the domain
Features, settings, and operations are the same as the ones in a physical environment.
How to use GDS in a control domain or an I/O root domain and manage disks used in a guest domain or an I/O root domain
A volume created in a control domain or an I/O root domain, or a file created on a volume can be used as a virtual disk in a guest domain or an I/O root domain.
The availability of a guest domain or an I/O root domain can be increased by placing a virtual disk used in a guest domain or an I/O root domain on a mirror volume created in a control domain or an I/O root domain.
How to use GDS in a guest domain and manage disks used in a guest domain
A virtual disk can be registered and managed in a local or shared class in a guest domain.
A shared disk used in a cluster system between guest domains must be registered with a shared class in a guest domain.
When registering a virtual disk with a class, specify the physical disk name with the cXdX format.
Other features, settings, and operations are the same as the ones in a physical environment.
Domains that use disks
Control
I/O root
Guest
Domains that use GDS
Control
a
b
b
I/O root
-
a
b
Guest
-
-
c

	Domains that use disks
Control	I/O root	Guest
Domains that use GDS	Control	a	b	b
I/O root	-	a	b
Guest	-	-	c

GDS: Global Disk Services

How to set b. is described as follows:

The following explains how to allocate a virtual disk in a guest domain by using GDS in a control domain. Also, the both setting methods for assigning a virtual disk to an I/O root domain by using GDS in a control domain and for assigning a virtual disk to a guest domain by using GDS in an I/O root domain are also the same.

How to assign a volume in a control domain to a guest domain as a virtual disk
Example 1) when exporting the existing volume0001 of the local class class0001 to the existing virtual disk server primary-vds0 as the volume vol0, and assigning it to the guest domain ldom0 as the virtual disk vdsik0.
```
# ldm add-vdsdev options=slice /dev/sfdsk/class0001/dsk/volume0001 vol0@primary-vds0
# ldm add-vdisk vdisk0 vol0@primary-vds0 ldom0
```
How to assign a file on a volume in a control domain to a guest domain as a virtual disk
Example 2) when creating the /LDoms/vdisk1.img file of 20 MB on the existing mirror volume of the root class and exporting it to the existing virtual server primary vds0 as the volume vol1 and assigning it to the guest domain ldom0 as the virtual disk vdisk1.
```
# mkfile 20g /LDoms/vdisk1.img
# ldm add-vdsdev /LDoms/vdisk1.img vol1@primary-vds0
# ldm add-vdisk vdisk1 vol1@primary-vds0 ldom0
```

See

For details on a setting procedure for a virtual disk, see Oracle VM administration guide.
For using GDS in a cluster system in Oracle VM environment, see "PRIMECLUSTER Installation and Administration Guide."

Note

Assign a file on a volume of the root class or a local class to a guest domain as a virtual disk in the following cases:
- When placing a system disk of a guest domain on a volume of a control domain.
- When placing a system disk of a guest domain on a volume of an I/O root domain.
- When placing a system disk of an I/O root domain on a volume of a control domain.
Specify the slice option (options=slice) by the ldm add-vdsdev command in the following cases:
- When assigning a volume of a control domain to a guest domain as a virtual disk.
- When assigning a volume of a control domain to an I/O root domain as a virtual disk.
- When assigning a volume of an I/O root domain to a guest domain as a virtual disk.
When managing a virtual disk by using GDS in a guest domain, assign the physical disk of a control domain to a guest domain as a full disk.
When making a service domain redundant, specify the timeout option of a virtual disk.
[Service domain redundancy]
There are the following two methods for making a service domain redundant:
- Assigning a shared disk as a virtual disk from a service domain which is different for each guest domain in a cluster between guest domains of PRIMECLUSTER.
- Assigning multiple disks as virtual disks from a service domain which is different for a disk to one guest domain and mirroring these virtual disks in a guest domain by using GDS.
[Specifying the timeout option]
When omitting the timeout option, or specifying 0 to the option, an I/O error does not occur even a service domain stops. The I/O will be restored after the service domain is recovered.
When specifying a value greater than 0 to the timeout option, an I/O error will occur after the time according to the value you specified.
(Note: An I/O error may not occur after the same seconds as the value you specified for the timeout option.)
The following shows how to specify the timeout option.
Example 1: Specifying 15 to the timeout when assigning a virtual disk.
```
# ldm add-vdisk timeout=15 vdisk0 disk0@primary-vds0 guest0
```
Example 2: Specifying 15 to the timeout for the assigned virtual disk.
```
# ldm set-vdisk timeout=15 vdisk0 guest0
```
For details on the timeout option, see Oracle VM administration guide.
When making a service domain redundant by using the mirroring function of GDS, do not register five or more disks that are assigned to the guest domain from one service domain to one class.
In the guest domain, when registering the virtual disk to the class and using hot spare function, spare disk different from the condition of the hot spare mode may be connected. Also, do not change the hot spare mode from default (external mode). When changing to internal mode, spare disk may not be connected.
A virtual disk is recognized as a device name of the /dev/[r]dsk/cXdXs0 format in a guest domain. Be careful not to make any mistakes for the device to be used because the different name is used from the device name of a control domain.
When live migration is done for the guest domain where GDS is used, adjust the timeout option of virtual disk so that I/O of virtual disk does not time out. If the timeout option value of virtual disk is shorter than the time for which I/O to the disk is restrained during the execution of live migration, I/O error may occur and then the slice becomes INVALID. For details of the timeout option, see manual of Oracle VM.
When using GDS on both service domain and guest domain, register the disk to be used only with guest domain to the Excluded Device List for both automatic resource registration and GDS in the service domain. Also, it is recommended in service domain and guest domain to create class with different names. For details on the Excluded Device List, see "A.2.25 Excluded Device List."