vzdump : bwlimit modified but no speed increase...

[XZed]

I posted my final tests results on other post.

http://www.proxmox.com/forum/showthread.php?p=14759#post14759

Could you read it, please ?

Thank you,

Sincerely,

 

[dietmar]

With raw format : 6 Mo/s backup

With raw format we need to read all data twice.

With qcow2 : quite 50 Mo/s backup....

We only need to reed allocated data once. I guess that explains the difference.

 

[XZed]

Well, many thanks for all your answers and support during my tests !

Now, i have to take the final choice : raw or qcow2 lol ...

Thank you.

 

[dietmar]

Now, i have to take the final choice : raw or qcow2 lol ...

Hint: qcow2 image grows as soon as you really use the disk.

 

[XZed]

Hint: qcow2 image grows as soon as you really use the disk.

What is your real thought ?

Are you talking about it as a pro or a con ?

For me, at least, it's a pro...

But, even if raw "displays" the whole disk size , it only really uses the used disk space...at least on all VM i tested..

Finally, i chose QCOW2 format !

In fact, RAW seemed better but i made various tests and i can confirm it : RAW backups too slow (you already explained me why !)

Thank you very much !

 

[dietmar]

What is your real thought ?

Are you talking about it as a pro or a con ?

As soon as you use space on the qcow2 disk it will grow, and it will be soon as large as the raw image (depends on the usage scenario). The backup will take as long as with raw disks.

But, even if raw "displays" the whole disk size , it only really uses the used disk space...at least on all VM i tested..

That is true. Nethertheless, we have to read the whole data (even the blocks containing zeros).

- Dietmar

 

[XZed]

That is true. Nethertheless, we have to read the whole data (even the blocks containing zeros).
- Dietmar

Oh, i hadn't think about it (read the zero blocks). Thanks !