What is PE (Physical Extents):
Extent is nothing but smallest allocatable unit of space in LVM. A physical volume is
broken into Physical Extents (PEs). One PE is the smallest unit of disk space you can allocate.
The PE and LE sizes are set at the time of VG creation and they are consistent throughout a volume group.
The default extent size is 4 MB.
Use of PE :
1. The PE size is only used for bookeeping, and has nothing to do with actual read or write performance. Smaller PE size allows more precise disk allocation. Larger PE size allows larger PV sizes, leading to larger VG maximum size.
2. WE use PE size to calculate total size of disk which can be allocated within that VG.
Max_PE_per_PV * PE size = Total disk size
admin_server:/] vgdisplay vg01 |egrep "PE Size|Max PE per PV"
Max PE per PV 4466
PE Size (Mbytes) 64
total size of disk =
4466 * 64
285824
285824 / 1024
279
279 GB
Note : The maximum number of PE are in the range 1 to 65535 in 11.31.
Extent is nothing but smallest allocatable unit of space in LVM. A physical volume is
broken into Physical Extents (PEs). One PE is the smallest unit of disk space you can allocate.
The PE and LE sizes are set at the time of VG creation and they are consistent throughout a volume group.
The default extent size is 4 MB.
Use of PE :
1. The PE size is only used for bookeeping, and has nothing to do with actual read or write performance. Smaller PE size allows more precise disk allocation. Larger PE size allows larger PV sizes, leading to larger VG maximum size.
2. WE use PE size to calculate total size of disk which can be allocated within that VG.
Max_PE_per_PV * PE size = Total disk size
admin_server:/] vgdisplay vg01 |egrep "PE Size|Max PE per PV"
Max PE per PV 4466
PE Size (Mbytes) 64
total size of disk =
4466 * 64
285824
285824 / 1024
279
279 GB
Note : The maximum number of PE are in the range 1 to 65535 in 11.31.
Thanks...
Kiran Jadhav
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