Creating a volume on SSD devices

This section explains how to create a volume on Solid State Disk (SSD) device.

You must upgrade the disk group to version 150 for SSD support. To upgrade the disk group, use the following command:

# vxdg upgrade diskgroup

where diskgroup is the name of the disk group to which the disk belongs.

The allocation behavior of vxassist changes with presence of SSD devices in a disk group.

Note:

If the disk group version is less than 150, vxassist will not honor media type of the device for making allocations.

The vxassist command allows you to specify Hard Disk Drive (HDD) or SSD devices for allocation using the mediatype attribute. For example, to create a volume myvol of size 1g on SSD disks in mydg, use the following command:

# vxassist -g mydg make myvol 1g mediatype:ssd

For example, to create a volume myvol of size 1g on HDD disks in mydg, use the following command:

# vxassist -g mydg make myvol 1g mediatype:hdd

If neither mediatype:hdd nor mediatype:ssd is specified, then mediatype:hdd is considered as default selection type which means only the HDD devices present in the disk group are considered for allocation.

If a mix of SSD devices and HDD devices are specified, the allocation is done only on HDD devices unless mediatype:ssd is explicitly specified. For example:

enclr1 : enclosure having all SSD devices
enclr2 : enclosure having all HDD devices
enclr3 : enclosure having mix of SSD and HDD devices

In the following command, volume myvol of size 1G is allocated on devices from enclr2 array (only HDD devices):

# vxassist -g mydg make myvol 1G enclr:enclr1 enclr:enclr2

In order to create a volume on SSD devices from enclr1 enclosure, following command should be used:

# vxassist -g mydg make myvol 1G enclr:enclr1 mediatype:ssd

If enclr3 is only specified, only hdd devices present in enclr3 are considered for allocation.

In the following two commands, volume myvol of size 1G is allocated on HDD devices from enclr3 array:

# vxassist -g mydg make myvol 1G enclr:enclr3 mediatype:hdd
# vxasisst -g mydg make myvol 1G enclr:enclr3

In order to allocate a volume on SSD devices from enclr3 enclosure, following command should be used:

# vxassist -g mydg make myvol 1G enclr:enclr3 mediatype:ssd

The allocation fails, if the command is specified in one of the following two ways:

# vxassist -g mydg make myvol 1G enclr:enclr1 mediatype:hdd

In the above case, volume myvol cannot be created as there are no HDD devices in enclr1 enclosure.

# vxassist -g mydg make myvol 1G enclr:enclr2 mediatype:ssd

In the above case, volume myvol cannot be created as there are no SSD devices in enclr2 enclosure.