topic Vsnap? in Disk Enclosures

Vsnap?

Domenico Viggiani — Tue, 03 May 2005 04:35:21 GMT

Hi,
I have a EVA3000 disk-array with Business-Copy license.
I read that EVA supports three types of clones:
- traditional snapshots, using same space of original Vdisk
- Vsnap or virtually capacity-free snapshot
- snapclone
I'm interested in Vsnap but I wasn't able to find this option in CommandView; I see only options for traditional snapshot.
How can I create a Vsnap?

Thanks

Re: Vsnap?

Uwe Zessin — Tue, 03 May 2005 04:51:17 GMT

Domenico,
I'm not sure which version of CV-EVA you have, but I have attached a picture from V3.3 where a 'Vsnap' is selected.

Re: Vsnap?

Domenico Viggiani — Tue, 03 May 2005 04:56:45 GMT

OK, thank you.
But related help says:
"Allocate on demand â Reserves the space a Vdisk requires on the physical disk, but only as data is stored in it."
Thus this is not a virtually capacity-free snapshot as marketing adverti

Re: Vsnap?

Uwe Zessin — Tue, 03 May 2005 05:02:04 GMT

I cannot follow your argument...

The original data *must* be stored somewhere for the snapshot to retain its point-in-time view when the data of the original virtual disk is changed.
How did you think a "virtually capacity-free" snapshot worked?

Re: Vsnap?

Domenico Viggiani — Tue, 03 May 2005 05:37:55 GMT

I thought that point-in-time snapshot was made by pointers to original data, with no use of space. Only next changes needed to be saved somewhere, incrementally filling space.

Re: Vsnap?

Uwe Zessin — Tue, 03 May 2005 05:56:59 GMT

And that is exactly how the "Vsnap" or "virtually capacity-free" snapshot works, except that it is called "Demand-allocated" in CV-EVA.

Re: Vsnap?

Domenico Viggiani — Tue, 03 May 2005 07:03:20 GMT

Well, now it works as I intended; just after creation:
- Capacity Used: 0 GB
- Initial Allocation: 0 GB
After some disk activity:
- Capacity Used: 2 GB
- Initial Allocation: 0 GB

Perpaphs, before I made some mistake.

Thank you for clarification