Hallo Chris,

it is not a question of a maximum vmdk files allowed on a single vmfs volume, but you should keep in mind, that a growing file is always worse compared to the thick disk /monolithic disk in ESX.

VMFS is build for large files:

E.g. The I/O placed to an object in one VMDK that itself (the file, not the volume) is bigger than 2GB can cause a multi I/O Operation on the LUN, because 1,2, or 3 VMDH slizes have to be updated by the system. Another problem is fragmentation, when the LUN is becoming full the single 2gbsparces can be placed on different sectors of the LUN so condurrent write or read access can make the LUN respond slowly.

In my opinion, leaving on -flat.vmdk is much better for any operation compared ro sparced disks. If you want to export your VMDKs you can use VCB and split the one -flat.vmdk back to many 2gbsparces on your backup volume e.g. FAT32 or NTFS or what ever.

Carsten