AIX : Create LV with poor man stripe

Hi all

I have just had SAN allocate 4*30 GB of disks and had created a new scalable vg and assigned the disks to it:

I used smitty to create vg and the command is:

x -y'vgdata1' hdisk82 hdisk83 hdisk84 hdisk85
root@aadcxs08 / : lsvg vgdata1
VOLUME GROUP:       vgdata1                  VG IDENTIFIER:  00c49e9a00004c00000001284ccb40cc
VG STATE:           active                   PP SIZE:        32 megabyte(s)
VG PERMISSION:      read/write               TOTAL PPs:      3828 (122496 megabytes)
MAX LVs:            256                      FREE PPs:       3828 (122496 megabytes)
LVs:                0                        USED PPs:       0 (0 megabytes)
OPEN LVs:           0                        QUORUM:         3 (Enabled)
TOTAL PVs:          4                        VG DESCRIPTORS: 4
STALE PVs:          0                        STALE PPs:      0
ACTIVE PVs:         4                        AUTO ON:        yes
MAX PPs per VG:     32768                    MAX PVs:        1024
LTG size (Dynamic): 256 kilobyte(s)          AUTO SYNC:      no
HOT SPARE:          no                       BB POLICY:      relocatable 
root@aadcxs08 / : 

does anyone know how i can change the BB Policy to NON RELOCATABLE? I couldn't find it on smitty.

but now im stuck with the mklv creation;

can someone please check if this is correct(pls dont say use smitty, just want the commands):

mklv -e x -t jfs2 -b -n -y elvdata09 vgdata1 <LP> hdisk82 hdisk83 hdisk84 hdisk85

Im not sure what the LP here is, is it total PP or max PV?

thanks in advance

rgds

priti

Hi,

why would you even possibly want a non-relocatable VG ? I don't think you can change it ...

mklv -y'<name_of_lv>' -t'jfs2' -x'<max_pp_in_lv>' rootvg <size_of_lv_in_pp>

where <max_pp_in_lv> is the size you want the lv to maximum grow to and <size_of_lv_in_pp> is the size you want it to be now. You can later extend a filesystem residing in this lv just with chfs up to the size of max without first growing the lv. It would be automatically spread (poor man striped) across all disks CURRENTLY in your volumegroup. If you later add more disks to your vg, than this lv would remain spread across the disks you have now as long as you don't run a reorg command - any newly created lv's would be spread across the new amount of disks.

If you want afterwards to create a filesystem within this created lv than you would do it i.e. like this (I assume an inline log, that you want it auto mounted after a system boot and rbrw mounted in my sample):

crfs -v jfs2 -d'<name_of_lv>' -m'<mountpoint>' -p'rw' -A yes -a options='rbrw' -a logname='INLINE'

This filesystem would have the size <size_of_lv_in_pp> from the mklv command.

Hope this helps
kind regards
zxmaus

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You say you are using LUNs out of a SAN: in this case it is irrelevant if you employ some striping algorithm in creating LVs or not. The SAN will distribute your disk accesses physically to several disks anyway.

Quite contrary, you could (very unlikely, but the possibility is non-zero) run into problems trying to stripe yourself when using an already striped medium: because of "Moir�"-like (interference) effects the diverse levels of striping could cancel out one another and change your pattern of disk access to the adverse.

I hope this helps.

bakunin

i followed zxmaus's steps (edited some options) and redid all my steps after i removed tge whole VG, this time i picked PP size as 4 MB, then created LV (max size) mounted the FS then i extended it all the way. but then setting up the LV and VG somehow used up 1Gb from the disks allocated so i ended up with a FS of 119GB. i pasted to the customer the output in MB :wink:

thanks all!

First off, thanks for writing a follow-up. Most people here do not and this way nobody knows if the suggested solution or the hint helped at all or not.

This might, depending on your requirements, be a problematic decision. You might want to read this and probably the other explanations in this thread to find out why.

I hope this helps.

bakunin

1 Like