I thought this one is quite interesting to blog about. Obviously for VMware guru’s that just old common knowledge.
Let’s start with defining what’s is the UUID made up from:
The UUID is comprised of four components :
- System Time
- CPU Timestamp
- Random Number
- MAC Address – Management Port uplink of the host used to resignature or create the datastore
Example:
~ # esxcfg-scsidevs -m
1 2 3 4 |
naa.60003ff44dc75adca1f1c655bd658363:1 /vmfs/devices/disks/naa.60003ff44dc75adca1f1c655bd658363:1 543217c6-8560f93c-4cbe-000c2956461b 0 DatastoreA mpx.vmhba1:C0:T1:L0:1 /vmfs/devices/disks/mpx.vmhba1:C0:T1:L0:1 556edb65-2ba42e84-6963-000c2956461b 0 locala naa.60003ff44dc75adc918e8c05f005c032:1 /vmfs/devices/disks/naa.60003ff44dc75adc918e8c05f005c032:1 5459f2d5-b4bedaf6-4def-000c2956461b 0 DatastoreC naa.60003ff44dc75adcaffb68e97f5457cd:1 /vmfs/devices/disks/naa.60003ff44dc75adcaffb68e97f5457cd:1 5432356c-0b33aed4-6ff0-000c2956461b 0 DatastoreB |
You can notice each datastore UUID ending with -00c2956461b as based on the management uplink:
The start of the UUID uses system time and CPU timestamp + random number to guarantee the uniqueness.