How to reduce the size of the main HD

[raid]

I have a new OVH server with proxmox installed and 2 HD 1TB in raid HW (mirroring).
I migrated 2 OpenVz VM and set up the ProxMox BackUp.
But when I created the Backup storage from proxmox panel I discovered the Backup folder size was 8GB only.

There is a way to allocate at least 50% of the available space for backup without having to install all over again?
thanks

 

[tom]

Post your current partitioning schema.

BTW, I do not recommend to store backups on the local host.

 

[raid]

Disk /dev/sda: 1000.2 GB, 1000203837440 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00094a71
Device Boot Start End Blocks Id System
/dev/sda1 * 1 1306 10485760+ 83 Linux
/dev/sda2 1306 121536 965746688 8e Linux LVM
/dev/sda3 121536 121601 525312 82 Linux swap / Solaris
Disk /dev/dm-0: 988.9 GB, 988920414208 bytes
255 heads, 63 sectors/track, 120229 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000
Disk /dev/dm-0 doesn't contain a valid partition table