>>> Is it possible to create multiple datastores on one virtual disk? Or every datastore should have it's own virtual disk?
VMware supports a single VMFS datastore on a given disk/VD/LUN.
If resizing the existing datasatore is not an option for you, then - assuming that you want to run ESXi in a supported way - your options are basically limited, to splitting the RAID into multiple VDs, which of course requires to backup the existing VMs, and restore them after re-configuring the RAID, and recreating the datatsore(s).
The unsupported option is to create a second VMFS partition (datastore) manually from the command line. However, I can't tell you whether this will cause issues.
Yes, You can create another datastore, but you will have to create new Partition
This can be done with partedUtil tool in ESXi
first you need to get the current partition layout
partedUtil getptbl /dev/disks/<Disk Name>
Then you will have to create a new partition with VMFS Type
partedUtil add "/dev/disks/t10.ATA_____Samsung_SSD_860_EVO_250GB_______________S3YJNF0JC02559E_____" gpt "10 8000000 488000000 AA31E02A400F11DB9590000C2911D1B8 0"
# gpt referes to the disk format.
# The number 488397168 is the last sector number of the drive.
# The next free partition number would be 10.
# 7086079 is the last sector number of the last partition.
# To create a partition we use partedUtil add
# 10 is the used partition number.
# 8000000 the first sector of the created partition.
# 488000000 the last sector of the created partition.
# AA31E02A400F11DB9590000C2911D1B8 is the partition type for VMware datastores.
# 0 refers to additional attributes like bootable. We dont need them.
After the partition was created we can format it using vmkfstools
Please let me know if you need more details.
---- Shane ----