Whats does the number denote which follows /vmfs/volumes/5ccfg379-5049xxxxx
This is the filesystem UUID which is generated when you format a disk or partition with VMFS or the installer formats its vfat volumes. It's separate from the physical disk ID (usually naa.XXXX or t10.XXXX) which is generated by the storage device.
You can get a list of all registered VMFS filesystems with this command:
# esxcli storage filesystem list
Mount Point Volume Name UUID Mounted Type Size Free
------------------------------------------------- --------------------- ----------------------------------- ------- ------ ------------ ------------
/vmfs/volumes/516fcbf8-669aa37a-61e9-040981e22300 Datastore1 516fcbf8-669aa37a-61e9-040981e22300 true VMFS-5 268167020544 266583670784
/vmfs/volumes/523a4564-6a4506c3-cf7f-10604b0aace1 Datastore2 523a4564-6a4506c3-cf7f-10604b0aace1 true VMFS-5 299842404352 285894246400
This tells you which VMFS volumes are mapped to which physical disk device:
# esxcfg-scsidevs -m
naa.6000eb38ccef4563000000000000043c:1 /vmfs/devices/disks/naa.6000eb38ccef4563000000000000043c:1 516fcbf8-669aa37a-61e9-040981e22300 0 Datastore1
naa.600508b1001c4fe29284c8a220cc4932:1 /vmfs/devices/disks/naa.600508b1001c4fe29284c8a220cc4932:1 523a4564-6a4506c3-cf7f-10604b0aace1 0 Datastore2