Contiguous policy causes lvextend problems

Hi

Summary:
I had a problem trying to extend an lv. It turns out that it was due to having a contiguous allocation policy. The error report wasn't helpful :)
Maybe this will help others searching the archive (I couldn't find anything useful)
Maybe someone could point me at what contiguous does?

so, I recently had a problem trying to lvextend an lv:

root@bao:~ # lvextend -l +2086 /dev/vg1/Myth
Extending logical volume Myth to 401.69 GB
Insufficient allocatable extents (4341) for logical volume Myth: 6427
required

Everything was setup correctly:
root@bao:~ # vgdisplay
--- Volume group ---
VG Name vg1
System ID

 Format                lvm2
 Metadata Areas        2
 Metadata Sequence No  3
 VG Access             read/write
 VG Status             resizable
 MAX LV                255
 Cur LV                1
 Open LV               1
 Max PV                255
 Cur PV                2
 Act PV                2
 VG Size               401.69 GB
 PE Size               64.00 MB
 Total PE              6427
 Alloc PE / Size       4341 / 271.31 GB
 Free  PE / Size       2086 / 130.38 GB
 VG UUID               T1gURQ-6CZM-axdh-UAHa-E1nd-fxEC-cwDLdq

root@bao:~ # pvdisplay
--- Physical volume ---

 PV Name               /dev/hdc3
 VG Name               vg1
 PV Size               271.31 GB / not usable 0  
 Allocatable           yes (but full)
 PE Size (KByte)       65536
 Total PE              4341
 Free PE               0
 Allocated PE          4341
 PV UUID               25Ngo9-LGNo-0Nsp-R826-C1Lc-5pD7-xh3GOX

--- Physical volume ---

 PV Name               /dev/hde2
 VG Name               vg1
 PV Size               130.38 GB / not usable 0  
 Allocatable           yes
 PE Size (KByte)       65536
 Total PE              2086
 Free PE               2086
 Allocated PE          0
 PV UUID               22hSvz-eARY-1AAq-5kko-whHH-QJRl-s94us5

--- NEW Physical volume ---
PV Name /dev/hdc
VG Name

 PV Size               279.40 GB
 Allocatable           NO
 PE Size (KByte)       0
 Total PE              0
 Free PE               0
 Allocated PE          0
 PV UUID               PWxvHH-uary-DgTx-Mk9K-UfoM-4gCs-fR1vzo

root@bao:~ # lvdisplay
--- Logical volume ---

 LV Name                /dev/vg1/Myth
 VG Name                vg1
 LV UUID                4hzmiM-9uSn-67Lm-ZWzS-YS2Q-gVtm-8HbTWW
 LV Write Access        read/write
 LV Status              available
 # open                 1
 LV Size                271.31 GB
 Current LE             4341
 Segments               1
 Allocation             contiguous
 Read ahead sectors     0
 Block device           254:0

but the allocation policy was 'contiguous'.
This isn't documented (that I could find) in the man pages - I am creating large (3-4Gb) files from a PVR and thought I'd try contiguous (in a kind of "what the heck, sounds about right" kinda way) It turns out that I needed to:
root@bao:~ # lvchange -C n /dev/vg1/Myth
Logical volume "Myth" changed
root@bao:~ # lvextend -l +2086 /dev/vg1/Myth
Extending logical volume Myth to 401.69 GB
Logical volume Myth successfully resized

Maybe a better error (or documentation of -C) is needed?

David