Saturday, March 10, 2018

Troubleshooting AIX file system extend issue

Troubleshooting AIX file system extend issue


extend /test on AIX client by 100 GB.

current size /test is 5GB.

chfs -a size=+100G /test

Error Message:  0516-787 extendlv: Maximum allocation for logical volume is 512


here found that PP size in VG is 128 MB and MAX limit of LP is 512,so maximum allowed File system extend is 65GB.

current LV MAX size
128 (PP size)*512(max LP limit of LV)= 65GB
here need to extend max limit so that we extend FS to 105 GB

MAX LP calculation 
1024*105=107520/128 =840 LP require to set in MAX LP .


extend LV's  maximum LP limit by using following command

chlv -x [no of lp] [lvname]
extendlv testlv [no. of LP]
smit chlv==>change characteristic to logical volume==>select LV=>find and enter MAX LP value and press enter

 and then execute filesystem extend command.

chfs -a size=+100G /test


How to Extend Physical volume in AIX volume group from storage end.


i came across this type of scenario when there was no free PP available on AIX volume group.
so i requested to storage guy to extend existing Physical volume.
following details requested storage guy to identify Lun at storage side
1.Lun ID 
2.Physical volume size
3.Lun name.

after Physical volume expanded from storage side AIX admin need to execute following command to add free PP in Physical volume.

#chvg -g testvg

-g   this flag scan disk in volume group and add addtional PP to Physical volume on AIX if its grown in size.

please dont  confuse between "-g" and "G" flag of capital "G" is for changing volume group to scalable format.remember that if there is stale partition on AIX volume group we cant proceed with this command ,first we need to sort out this issue.

In AIX there are three types of volume group .

1.normal -32 PV
2.Big-128 PV
3.scalable-1024 PV

command example:

#chvg -B vgname  -convert volume group to Big type which can accommodate 128 physical volume.there must be no stale partition before executing this command 

#chvg -G vgname -covert to scalable volume group.
while executing above command please make sure that there is no stale PP on volume group.
also there is free PP available on each physical volume to accommodate VGDA expansion and most important AIX volume group must be varied off state.


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