Description

How to create a VxVM volume with a mix of HDD and SSD disks

VxVM(Veritas Volume Manager) will automatically detect the media type of each disk it discovers as either SSD or HDD. VxVM does not allow the creation of a volume that is a mixture of HDD and SSD disks by default.

Example error when trying to create a volume with a hdd and ssd disk:

VxVM vxassist ERROR V-5-1-15315 Cannot allocate space for 409600 block volume: Not enough HDD devices that meet specification. Use mediatype:ssd allocation attribute to consider SSD devices for allocation.
 

This is by design since the volume will be limited by the slowest disk. 

Veritas does not recommend creating a volume that is a mix of HDD and SSD.

If it is necessary to create a volume that is a mix of the two media types then it is possible by changing the "mediatype" of a disk to match the existing disks media type. 

Change the media type on the new disk to either "ssd" or "hdd" so it matches the existing disk media type.
# vxdisk -f set mediatype=ssd

Example
# vxdisk -f set emc0_0290 mediatype=ssd

To show the media type detected by VxVM use the following command. This is the detected type so it won't change:
# vxdisk -p  list | grep MEDIA_TYPE

Example:
# vxdisk -p  list emc0_0290 | grep MEDIA_TYPE
MEDIA_TYPE          : hdd

If the media type was changed then this can be seen as a tag with:
# vxdisk -v list | grep vxmediatype

Example:
[root@server101 ~]# vxdisk -v list emc0_0290 | grep mediatype
 tag      vxmediatype=ssd

When "vxmediatype" differs from the detected type "MEDIA_TYPE" then the "media_mismatch" flag is seen on the disk.

# vxdisk list
DEVICE          TYPE            DISK         GROUP        STATUS
emc0_0290    auto:cdsdisk    -            -            online media_mismatch