A file or volume (for example from ZFS or Solaris Volume Manager) is exported either as a full disk or as single-slice disk depending on whether the slice option is set.
If you do not set the slice option, a file or volume is exported as a full disk. In that case, virtual disk drivers (vds and vdc) forward I/O from the virtual disk and manage the partitioning of the virtual disk. The file or volume eventually becomes a disk image containing data from all slices of the virtual disk and the metadata used to manage the partitioning and disk structure.
When a blank file or volume is exported as full disk, it appears in the guest domain as an unformatted disk; that is, a disk with no partition. Then you need to run the format command in the guest domain to define usable partitions and to write a valid disk label. Any I/O to the virtual disk fails while the disk is unformatted.
service# mkfile 100m /ldoms/domain/test/fdisk0
The size of the file defines the size of the virtual disk. This example creates a 100-Mbyte blank file to get a 100-Mbyte virtual disk.
primary# ldm add-vdsdev /ldoms/domain/test/fdisk0 fdisk0@primary-vds0
In this example, the slice option is not set, so the file is exported as a full disk.
For example, assign the disk (fdisk) to guest domain ldg1.
primary# ldm add-vdisk fdisk fdisk0@primary-vds0 ldg1
A full disk is a regular disk with eight slices.
The following example shows how to list the disk, c0d5, and verify that it is accessible and is a full disk.
ldg1# ls -1 /dev/dsk/c0d5s* /dev/dsk/c0d5s0 /dev/dsk/c0d5s1 /dev/dsk/c0d5s2 /dev/dsk/c0d5s3 /dev/dsk/c0d5s4 /dev/dsk/c0d5s5 /dev/dsk/c0d5s6 /dev/dsk/c0d5s7
The following example shows how to create a ZFS volume, zdisk0, to use as a full disk:
service# zfs create -V 100m ldoms/domain/test/zdisk0
The size of the volume defines the size of the virtual disk. This example creates a 100-Mbyte volume to result in a 100-Mbyte virtual disk.
primary# ldm add-vdsdev /dev/zvol/dsk/ldoms/domain/test/zdisk0 \ zdisk0@primary-vds0
In this example, the slice option is not set so the file is exported as a full disk.
The following example shows how to assign the volume, zdisk0, to the guest domain ldg1:
primary# ldm add-vdisk zdisk0 zdisk0@primary-vds0 ldg1
A full disk is a regular disk with eight slices.
The following example shows how to list the disk, c0d9, and verify that it is accessible and is a full disk:
ldg1# ls -1 /dev/dsk/c0d9s* /dev/dsk/c0d9s0 /dev/dsk/c0d9s1 /dev/dsk/c0d9s2 /dev/dsk/c0d9s3 /dev/dsk/c0d9s4 /dev/dsk/c0d9s5 /dev/dsk/c0d9s6 /dev/dsk/c0d9s7
If the slice option is set, then the file or volume is exported as a single-slice disk. In that case, the virtual disk has only one partition (s0), which is directly mapped to the file or volume back end. The file or volume only contains data written to the virtual disk with no extra data like partitioning information or disk structure.
When a file or volume is exported as a single-slice disk, the system simulates a fake disk partitioning which makes that file or volume appear as a disk slice. Because the disk partitioning is simulated, you do not create partitioning for that disk.
The following example shows how to create a ZFS volume, zdisk0, to use as a single-slice disk.
service# zfs create -V 100m ldoms/domain/test/zdisk0
The size of the volume defines the size of the virtual disk. This example creates a 100-Mbyte volume to get a 100-Mbyte virtual disk.
primary# ldm add-vdsdev options=slice /dev/zvol/dsk/ldoms/domain/test/zdisk0 \ zdisk0@primary-vds0
The following shows how to assign the volume, zdisk0, to guest domain ldg1.
primary# ldm add-vdisk zdisk0 zdisk0@primary-vds0 ldg1
ldg1# ls -1 /dev/dsk/c0d9s* /dev/dsk/c0d9s0 /dev/dsk/c0d9s1 /dev/dsk/c0d9s2 /dev/dsk/c0d9s3 /dev/dsk/c0d9s4 /dev/dsk/c0d9s5 /dev/dsk/c0d9s6 /dev/dsk/c0d9s7
If you have a configuration exporting volumes as virtual disks, volumes are now exported as full disks instead of single-slice disks. To preserve the old behavior and to have your volumes exported as single-slice disks, you need to do either of the following:
Use the ldm set-vdsdev command in Oracle VM Server for SPARC 3.5 software, and set the slice option for all volumes you want to export as single-slice disks. See the ldm(1M) man page.
Add the following line to the /etc/system file on the service domain.
set vds:vd_volume_force_slice = 1
For information about correctly creating or updating /etc/system property values, see Updating Property Values in the /etc/system File.
|
This section includes guidelines for exporting a file and a disk slice as a virtual disk.
Using the loopback file (lofi) driver to export a file as a virtual disk adds an extra driver layer and affects performance of the virtual disk. Instead, you can directly export a file as a full disk or as a single-slice disk. See File and Volume Exporting.
To export a slice as a virtual disk either directly or indirectly (for example through a Solaris Volume Manager volume), ensure that the slice does not start on the first block (block 0) of the physical disk by using the prtvtoc command.
If you directly or indirectly export a disk slice which starts on the first block of a physical disk, you might overwrite the partition table of the physical disk and make all partitions of that disk inaccessible.