[one-users] qcow2 images in datastores and as volatile disks

[Schroeder, Nils]

Hello,

I am trying to understand how opennebula handles the different image types. So I attach a volatile disk to my vm:

DISK  = [ TYPE = "fs",
          SIZE = 40000,
          FORMAT = "qcow2",
          DRIVER = qcow2]

1.: I have to set FORMAT = "qcow2" so qemu-img create is used to create the image file. But this way I can not specify a filesystem to be created, right? I have to manually format the disk after vm booted (of curse I can use contextualisation to do this part). Is there a way to tell opennebula to create qcow2 img and then format it with ext3?

2.: The main reason why I want to use qcow2 is thin provisioning in the meaning of empty disk does not use $max_size at our storage. For testing I created a disks like:

DISK  = [ TYPE = "fs",
          SIZE = 40000,
          FORMAT = "ext3"]

DISK  = [ TYPE = "fs",
          SIZE = 40000,
          FORMAT = "raw"]

I saw that even this disks only took ~750Mb on our NFS server. Can someone explain why, I expected that these raw (or raw with ext3 filesystem on it) will take the whole 40k Mb on our storage.

3.: The transfer manager ist attached to a datastore and not to a image. So I can not put qcow2 and raw images into the same datastore. Is there a reason for that? Why can't we attach the tm to a image instead of datastore? but I can put qcow2 images into shared tm datastore if the vm template overrides this by setting driver=qcow2, right?

Up to now I only thought about different datastores are different storage locations and different redundancy zones/slas/performance classes. Any clearification is appreciated

Thanks for your help,
Nils Schröder

OHG mit Sitz in Oldenburg; Registergericht Oldenburg HR A 1548;
Persönlich haftende geschäftsführende Gesellschafterin: Neumüller CeWe Color Stiftung, Oldenburg
Vorstand: Dr. Rolf Hollander, Vorsitzender; Harald H. Pirwitz, Felix Thalmann, Frank Zweigle, Dr. Michael Fries;
Geschäftsführer: Dr. Reiner Fageth, Andreas F.L. Heydemann, Dr. Olaf Holzkämper

Persönlich haftende Gesellschafterin: CeWe Color Holding AG, Oldenburg, Registergericht Oldenburg HR B 2956
Vorstand: Dr. Rolf Hollander, Vorsitzender; Andreas F.L. Heydemann, Dr. Reiner Fageth, Dr. Olaf Holzkämper
Aufsichtsrat: Otto Korte, Vorsitzender
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