[linux-lvm] lvm2 disk replacement

[cwinl]

hi,all
 
i have a DELL PE2800 server with 10 300GB disks.i make 3 PV which are 3
RAID0.then a LV cross the whole 3 PV.
now , one of RAID0 is unstable.
so i want to change disk.
but i can't lose data.
 
here is 'df' information:
 
/dev/mapper/nicvg-niclv       2.0T  774G  1.2T  40% /ftproot
 
and here is 'pvscan' information:
 
ftp:~# pvscan
  /dev/hda: open failed: No medium found
  PV /dev/sdb1   VG nicvg   lvm2 [838.09 GB / 0    free]
  PV /dev/sdc1   VG nicvg   lvm2 [558.72 GB / 0    free]
  PV /dev/sdd1   VG nicvg   lvm2 [558.72 GB / 0    free]
  Total: 3 [1.91 TB] / in use: 3 [1.91 TB] / in no VG: 0 [0   ]
 
the unstable PV is /dev/sdb1
 
i want to move data from /dev/sdb1 to the reset PV such as /dev/sdc1 and
/dev/sdd1.
i think the disk space is enough .
but when i use command 'pvmove -v /dev/sdb1' i got wrong info:
 
ftp:~# pvmove -v /dev/sdb1
    Finding volume group "nicvg"
  No extents available for allocation
 
my question is :
the reset of disk space is 1.2TB
but why 'pvscan' say free space is zero?
why i can't move data?
how can i solve the problem?
 
don't say add another disk to the server. i had added 10 disks to it and
there is no space to plug even one.