Question & Answer
Question
Why is my available space not the same as the size of the disk?
Cause
LVM uses the first PP for metadata. Depending on PP size, the metadata may span multiple PPs. If the PP size is larger than metadata, all other space in PP is unused.
Answer
For example, see below where hdisk3 is added to a vg:
# bootinfo -s hdisk3
10240
Create a vg where pp size is 1024 MB:
# mkvg -s 1024 -f hdisk3
vg01
# lsvg vg01
VOLUME GROUP: vg01 VG IDENTIFIER: 00c64c5700004c000000018085c99d1f
VG STATE: active PP SIZE: 1024 megabyte(s)
VG PERMISSION: read/write TOTAL PPs: 9 (9216 megabytes)
MAX LVs: 256 FREE PPs: 9 (9216 megabytes)
LVs: 0 USED PPs: 0 (0 megabytes)
OPEN LVs: 0 QUORUM: 2 (Enabled)
TOTAL PVs: 1 VG DESCRIPTORS: 2
STALE PVs: 0 STALE PPs: 0
ACTIVE PVs: 1 AUTO ON: yes
MAX PPs per VG: 32512
MAX PPs per PV: 1016 MAX PVs: 32
LTG size (Dynamic): 512 kilobyte(s) AUTO SYNC: no
HOT SPARE: no BB POLICY: relocatable
PV RESTRICTION: none INFINITE RETRY: no
DISK BLOCK SIZE: 512 CRITICAL VG: no
FS SYNC OPTION: no CRITICAL PVs: no
ENCRYPTION: no
You would expect Total PPs to show 10240 MB, the size of the disk added. However LVM uses the first PP for metadata.
So the size of the disk (10240 MB) - PP size (1024 MB) = 9216 MB, which is what we see as size of total PPs.
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Document Information
Modified date:
09 May 2022
UID
ibm16569259