關于這個問題我們首先來看一下AIX的vg的3種類型：
original vg 普通卷組
big vg 大卷組
scalable vg 動態的或者可擴展的卷組
如何快速區分這三組卷組呢？
通過其參數MAX PVS，上述3個類型的卷組對應的限制是：32、128、1024;除此之外，還可以通過readvgda命令來讀取pv的元數據判斷。
好了，實際來看幾個例子。

db1:/#uname -a
AIX db1 1 6 00F7B72A4C00
db1:/#oslevel -r
6100-07
這是一臺aix6.1下的環境，含有rootvg和vg01兩個卷組：
db1:/#lsvg -o
vg01
rootvg
其中rootvg當然是系統使用的vg，vg01是準備用來被oracle使用的。
現有pv如下：
db1:/#lspv
hdisk0????????? 00f7b72ab2370b93??????????????????? rootvg????????? active???? ?
hdisk1????????? 00f7b72aacb2dab0??????????????????? rootvg????????? active???? ?
hdisk2????????? none??????????????????????????????? None?????????????????????? ?
hdisk3????????? none??????????????????????????????? None?????????????????????? ?
hdisk4????????? none??????????????????????????????? None?????????????????????? ?
hdisk5????????? none??????????????????????????????? None?????????????????????? ?
hdisk6????????? none??????????????????????????????? None?????????????????????? ?
hdisk7????????? none??????????????????????????????? None?????????????????????? ?
hdisk8????????? 00f7b72af78cefac??????????????????? vg01??????????? active???? ?
hdisk9????????? 00f7b72af78cf3f9??????????????????? vg01??????????? active???? ?
hdisk10???????? 00f7b72af78cf834??????????????????? vg01??????????? active???? ?
hdisk11???????? 00f7b72af7a7bf97??????????????????? diskhb???????????????????? ?
現在我們通過MAX PVS這個參數判斷卷組類型：
db1:/#lsvg rootvg
VOLUME GROUP:?????? rootvg?????????????????? VG IDENTIFIER:? 00f7b72a00004c000000013bb2371f49
VG STATE:?????????? active?????????????????? PP SIZE:??????? 512 megabyte(s)
VG PERMISSION:????? read/write?????????????? TOTAL PPs:????? 1116 (571392 megabytes)
MAX LVs:??????????? 256????????????????????? FREE PPs:?????? 650 (332800 megabytes)
LVs:??????????????? 16?????????????????????? USED PPs:?????? 466 (238592 megabytes)
OPEN LVs:?????????? 13?????????????????????? QUORUM:???????? 1 (Disabled)
TOTAL PVs:????????? 2??????????????????????? VG DESCRIPTORS: 3
STALE PVs:????????? 0??????????????????????? STALE PPs:????? 0
ACTIVE PVs:???????? 2??????????????????????? AUTO ON:??????? yes
MAX PPs per VG:???? 32512??????????????????????????????????? ?
MAX PPs per PV:???? 1016???????????????????? MAX PVs:??????? 32
LTG size (Dynamic): 1024 kilobyte(s)???????? AUTO SYNC:????? no
HOT SPARE:????????? no?????????????????????? BB POLICY:????? relocatable
PV RESTRICTION:???? none???????????????????? INFINITE RETRY: no
db1:/#lsvg vg01
VOLUME GROUP:?????? vg01???????????????????? VG IDENTIFIER:? 00f7b72a00004c000000013ef78cf9e8
VG STATE:?????????? active?????????????????? PP SIZE:??????? 256 megabyte(s)
VG PERMISSION:????? read/write?????????????? TOTAL PPs:????? 3597 (920832 megabytes)
MAX LVs:??????????? 256????????????????????? FREE PPs:?????? 3565 (912640 megabytes)
LVs:??????????????? 2??????????????????????? USED PPs:?????? 32 (8192 megabytes)
OPEN LVs:?????????? 0??????????????????????? QUORUM:???????? 2 (Enabled)
TOTAL PVs:????????? 3??????????????????????? VG DESCRIPTORS: 3
STALE PVs:????????? 0??????????????????????? STALE PPs:????? 0
ACTIVE PVs:???????? 3??????????????????????? AUTO ON:??????? no
MAX PPs per VG:???? 32768??????????????????? MAX PVs:??????? 1024
LTG size (Dynamic): 256 kilobyte(s)????????? AUTO SYNC:????? no
HOT SPARE:????????? no?????????????????????? BB POLICY:????? relocatable
MIRROR POOL STRICT: off????????????????????????????????????? ?
PV RESTRICTION:???? none???????????????????? INFINITE RETRY: no
根據參數我們可以得出rootvg是original vg，而vg01是scalable vg，通過readvgda也可以得出相同的結論：
db1:/#readvgda hdisk0? | grep -i type
.....??? readvgda_type: smallvg
vgtype:???????? 0
對應的0就是original vg了，其他的還有1對應big vg，2對應scalable vg。

接下來我們看下關于4k offset的問題。首先分別在original和scalable vg創建2個lv，一共4個lv：
db1:/#/usr/sbin/mklv -y'lv_system03_512' -t'raw' rootvg 4
lv_system03_512
db1:/#/usr/sbin/mklv -T O -y'lv_system04_512' -t'raw' rootvg 4
lv_system04_512
db1:/#/usr/sbin/mklv -y'lv_system01_4g' -t'raw' vg01 16
lv_system01_4g
db1:/#/usr/sbin/mklv -T O -y'lv_system02_4g' -t'raw' vg01 16
lv_system02_4g
查看下創建出來的lv：
db1:/#lslv lv_system03_512
LOGICAL VOLUME:???? lv_system03_512??????? VOLUME GROUP:?? rootvg
LV IDENTIFIER:????? 00f7b72a00004c000000013bb2371f49.15 PERMISSION:???? read/write
VG STATE:?????????? active/complete??????? LV STATE:?????? closed/syncd
TYPE:?????????????? raw??????????????????? WRITE VERIFY:?? off
MAX LPs:??????????? 512??????????????????? PP SIZE:??????? 512 megabyte(s)
COPIES:???????????? 1????????????????????? SCHED POLICY:?? parallel
LPs:??????????????? 4????????????????????? PPs:??????????? 4
STALE PPs:????????? 0????????????????????? BB POLICY:????? relocatable
INTER-POLICY:?????? minimum??????????????? RELOCATABLE:??? yes
INTRA-POLICY:?????? middle???????????????? UPPER BOUND:??? 32
MOUNT POINT:??????? N/A??????????????????? LABEL:????????? None
MIRROR WRITE CONSISTENCY: on/ACTIVE???????????????????????????? ?
EACH LP COPY ON A SEPARATE PV ?: yes?????????????????????????????????? ?
Serialize IO ?:???? NO??????????????????????????????????? ?
INFINITE RETRY:???? no??????????????????????????????????? ?
db1:/#lslv lv_system04_512
LOGICAL VOLUME:???? lv_system04_512??????? VOLUME GROUP:?? rootvg
LV IDENTIFIER:????? 00f7b72a00004c000000013bb2371f49.16 PERMISSION:???? read/write
VG STATE:?????????? active/complete??????? LV STATE:?????? closed/syncd
TYPE:?????????????? raw??????????????????? WRITE VERIFY:?? off
MAX LPs:??????????? 512??????????????????? PP SIZE:??????? 512 megabyte(s)
COPIES:???????????? 1????????????????????? SCHED POLICY:?? parallel
LPs:??????????????? 4????????????????????? PPs:??????????? 4
STALE PPs:????????? 0????????????????????? BB POLICY:????? relocatable
INTER-POLICY:?????? minimum??????????????? RELOCATABLE:??? yes
INTRA-POLICY:?????? middle???????????????? UPPER BOUND:??? 32
MOUNT POINT:??????? N/A??????????????????? LABEL:????????? None
MIRROR WRITE CONSISTENCY: on/ACTIVE???????????????????????????? ?
EACH LP COPY ON A SEPARATE PV ?: yes?????????????????????????????????? ?
Serialize IO ?:???? NO??????????????????????????????????? ?
INFINITE RETRY:???? no????????? ?

db1:/#lslv lv_system01_4g
LOGICAL VOLUME:???? lv_system01_4g???????? VOLUME GROUP:?? vg01
LV IDENTIFIER:????? 00f7b72a00004c000000013ef78cf9e8.1 PERMISSION:???? read/write
VG STATE:?????????? active/complete??????? LV STATE:?????? closed/syncd
TYPE:?????????????? raw??????????????????? WRITE VERIFY:?? off
MAX LPs:??????????? 512??????????????????? PP SIZE:??????? 256 megabyte(s)
COPIES:???????????? 1????????????????????? SCHED POLICY:?? parallel
LPs:??????????????? 16???????????????????? PPs:??????????? 16
STALE PPs:????????? 0????????????????????? BB POLICY:????? relocatable
INTER-POLICY:?????? minimum??????????????? RELOCATABLE:??? yes
INTRA-POLICY:?????? middle???????????????? UPPER BOUND:??? 1024
MOUNT POINT:??????? N/A??????????????????? LABEL:????????? None
MIRROR WRITE CONSISTENCY: on/ACTIVE???????????????????????????? ?
EACH LP COPY ON A SEPARATE PV ?: yes?????????????????????????????????? ?
Serialize IO ?:???? NO??????????????????????????????????? ?
INFINITE RETRY:???? no??????????????????????????????????? ?
DEVICESUBTYPE:????? DS_LVZ?????????????????????????????????????? ?
COPY 1 MIRROR POOL: None????????????????????????????????? ?
COPY 2 MIRROR POOL: None????????????????????????????????? ?
COPY 3 MIRROR POOL: None????????????????????????????????? ?
db1:/#lslv lv_system02_4g
LOGICAL VOLUME:???? lv_system02_4g???????? VOLUME GROUP:?? vg01
LV IDENTIFIER:????? 00f7b72a00004c000000013ef78cf9e8.2 PERMISSION:???? read/write
VG STATE:?????????? active/complete??????? LV STATE:?????? closed/syncd
TYPE:?????????????? raw??????????????????? WRITE VERIFY:?? off
MAX LPs:??????????? 512??????????????????? PP SIZE:??????? 256 megabyte(s)
COPIES:???????????? 1????????????????????? SCHED POLICY:?? parallel
LPs:??????????????? 16???????????????????? PPs:??????????? 16
STALE PPs:????????? 0????????????????????? BB POLICY:????? relocatable
INTER-POLICY:?????? minimum??????????????? RELOCATABLE:??? yes
INTRA-POLICY:?????? middle???????????????? UPPER BOUND:??? 1024
MOUNT POINT:??????? N/A??????????????????? LABEL:????????? None
MIRROR WRITE CONSISTENCY: on/ACTIVE???????????????????????????? ?
EACH LP COPY ON A SEPARATE PV ?: yes?????????????????????????????????? ?
Serialize IO ?:???? NO??????????????????????????????????? ?
INFINITE RETRY:???? no??????????????????????????????????? ?
DEVICESUBTYPE:????? DS_LVZ?????????????????????????????????????? ?
COPY 1 MIRROR POOL: None????????????????????????????????? ?
COPY 2 MIRROR POOL: None????????????????????????????????? ?
COPY 3 MIRROR POOL: None????????????????????????????????? ?

結合結果，有如下結論：
0. Origninal VG無論是否使用“-T O”參數，創建出來的lv都是DS_LV;
1. Scalable VG無論是否使用“-T O”參數，創建出來的lv都是DS_LVZ;
2. Big VG使用“-T O”參數創建出來的lv是DS_LVZ類型，否則是DS_LV類型。

通過查看lv的屬性DEVICESUBTYPE：DS_LVZ也就是沒有偏移的lv，初次之外Oracle也提供了一個工具來檢查是有offset：
db1:/#ls -l /dev/lv_*
brw-rw----??? 1 root???? system?????? 53,? 1 Jul 02 09:12 /dev/lv_system01_4g
brw-rw----??? 1 root???? system?????? 53,? 2 Jul 02 09:15 /dev/lv_system02_4g
brw-rw----??? 1 root???? system?????? 10, 15 Jul 02 09:16 /dev/lv_system03_512
brw-rw----??? 1 root???? system?????? 10, 16 Jul 02 09:18 /dev/lv_system04_512
db1:/#ls -l /dev/rlv_*
crw-rw----??? 1 root???? system?????? 53,? 1 Jul 02 09:12 /dev/rlv_system01_4g
crw-rw----??? 1 root???? system?????? 53,? 2 Jul 02 09:15 /dev/rlv_system02_4g
crw-rw----??? 1 root???? system?????? 10, 15 Jul 02 09:16 /dev/rlv_system03_512
crw-rw----??? 1 root???? system?????? 10, 16 Jul 02 09:18 /dev/rlv_system04_512
其中每個lv對應有快設備和字符設備，oracle使用的是字符設備：
db1:/#chown oracle:oinstall /dev/rlv_*
db1:/#chmod 700 /dev/rlv_*
db1:/#ls -l /dev/rlv_*
crwx------??? 1 oracle?? oinstall???? 53,? 1 Jul 02 09:12 /dev/rlv_system01_4g
crwx------??? 1 oracle?? oinstall???? 53,? 2 Jul 02 09:15 /dev/rlv_system02_4g
crwx------??? 1 oracle?? oinstall???? 10, 15 Jul 02 09:16 /dev/rlv_system03_512
crwx------??? 1 oracle?? oinstall???? 10, 16 Jul 02 09:18 /dev/rlv_system04_512
由于該工具只能檢查被用于數據文件的lv，因此只能在被使用之后檢查，現在先刪除掉上述4個lv，之后重新創建用于測試，注意要用root用戶執行：
db1:/oracle$ dbfsize /dev/rlv_system01_4g
/dev/rlv_system01_4g: Header block magic number is bad; trying raw file format...
/dev/rlv_system01_4g: Header block magic number is bad
db1:/oracle$ dbfsize /dev/rlv_system03_512
??????? /dev/rlv_system03_512: Header block magic number is bad
刪除? rmlv -f 'rlv_system01_4g' rmlv -f 'rlv_system02_4g' rmlv -f 'rlv_system03_512' rmlv -f 'rlv_system04_512'

在創建數據庫之后重新執行下如下結果就可以結果：
db1:/#/oracle/app/oracle/product/10.2/db1/bin/dbfsize /dev/lv_control_01

Database file: /dev/lv_control_01
Database file type: raw device without 4K starting offset
Database file size: 334 16384 byte blocks???? ?
?
這個是沒有offset的.
接著來看下有offset的結果：
/usr/sbin/mklv -y'lvtest' -t'raw' rootvg 1?????????? ?
chown oracle:oinstall /dev/rlvtest
chmod 700 /dev/rlvtest
db1:/#su - oracle
db1:/oracle$ sqlplus "/as sysdba"

SQL*Plus: Release 10.2.0.4.0 - Production on Tue Jul 2 11:50:32 2013

Copyright (c) 1982, 2007, Oracle.? All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> create tablespace gtlions datafile '/dev/rlvtest' size 10m;

Tablespace created.

SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
db1:/oracle$ /oracle/app/oracle/product/10.2/db1/bin/dbfsize /dev/lvtest? ?

Database file: /dev/lvtest
Database file type: raw device??? ?
Database file size: 1280 8192 byte blocks??? ?
而且使用有offset的lv創建表空間的時候在后臺日志也會做相應的記錄并提出建議：
create tablespace gtlions datafile '/dev/rlvtest' size 10m
WARNING: You are creating datafile /dev/rlvtest.
WARNING: Oracle recommends creating new datafiles on devices with zero offset. The command "/usr/sbin/mklv -y LVname -T O -w n -s n -r n VGname NumPPs" can be used. Please contact Oracle customer support for more details.
WARNING: You are creating/reusing datafile /dev/rlvtest.
WARNING: Oracle recommends creating new datafiles on devices with zero offset. The command "/usr/sbin/mklv -y LVname -T O -w n -s n -r n VGname NumPPs" can be used. Please contact Oracle customer support for more details.
Completed: create tablespace gtlions datafile '/dev/rlvtest' size 10m ?
-EOF-

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