[CentOS] formatting large volume
Stephen Harris
lists at spuddy.org
Wed Oct 15 17:34:39 UTC 2008
On Wed, Oct 15, 2008 at 09:52:03AM -0700, Craig White wrote:
> I have done the pgcreate and tested lvcreate but wonder about
> 'setphysicalextentsize' because in the man page, it states, "The default
> of 4 MB leads to a maximum logical volume size of around 256GB" which
> makes me think that if I want one volume when this is all done, I have
> to increase that value.
The man page for "vgcreate" says "there is a limit of 65534 extents in
each logical volume" but only for *lvm1* format. lvm2 format doesn't
have such restrictions.
I used default values for my 4Tbyte array (5*1Tbyte disk in a md raid5)
under CentOS 4.
% fdisk -l /dev/md3
Disk /dev/md3: 4000.8 GB, 4000808697856 bytes
2 heads, 4 sectors/track, 976759936 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
% pvdisplay /dev/md3
--- Physical volume ---
PV Name /dev/md3
VG Name Raid5
PV Size 3.64 TB / not usable 320.00 KB
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 953867
Free PE 0
Allocated PE 953867
PV UUID NngvXK-4tqJ-xNtG-UnDL-Rin0-RHIl-xZ2wzI
% vgdisplay Raid5
--- Volume group ---
VG Name Raid5
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 1
Max PV 0
Cur PV 1
Act PV 1
VG Size 3.64 TB
PE Size 4.00 MB
Total PE 953867
Alloc PE / Size 953867 / 3.64 TB
Free PE / Size 0 / 0
VG UUID mKSI0h-26i7-5LK5-vwpX-GY3a-Bjiv-xX4q8n
% lvdisplay Raid5/Media
--- Logical volume ---
LV Name /dev/Raid5/Media
VG Name Raid5
LV UUID c8x4Ip-R1wq-n9An-NM6B-IuBs-U61L-kfVgAU
LV Write Access read/write
LV Status available
# open 1
LV Size 3.64 TB
Current LE 953867
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:5
> Does this make sense?
Try using "pvcreate", "vgcreate" and "lvcreate" with no special options
and see what happens. It worked for me!
The default in CentOS should be lvm2; you can see that's what was
created on mine by the "Format" line in the vgdisplay output.
Format lvm2
--
rgds
Stephen
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